How do you know how well your comic compared to nice/good comics?

It's difficult!

For me, I found that learning to analyse or critique other people's work helped a lot. I was really overconfident when I started making comics, because I was a small-town artistic prodigy as a kid, always being told how exceptional I was. I thought I was practically pro standard and that all the polish stuff that made book art look different from mine was just like..."IDK they just put it into the printer and that stuff just happens".

When I started spending time around more experienced aspiring comics creators online, I came down to earth with a bump. "Oh, you need to make your gutters more consistent", "Hey, your shot distance and angles could do with being more varied", "Hm, maybe look up some comics fonts and read this tutorial on speech bubbles", "Here's a good book on anatomy" etc. I realised that other people didn't just get given that polish, they created it by themselves through pure effort.

I started to study comics I liked on more than just a surface level, and the closer I looked, the more I realised how far I needed to climb. Yeah, my anatomy was good for a teenager, and wasn't bad when characters were in fairly neutral poses and viewed from a straight-on angle, but my skills simply weren't good enough to draw to that level while changing the angle up, I was limited in body types I could draw, and on poses. So I started to study really hard.

The devil is in the details. When looking at other people's comics, look at things like their colour palette choices, their line quality, their design elements like fonts and speech bubbles, their visual storytelling, or things like the proportions or sense of mass on characters. When you find somebody who really excels at something, try to think about what you can learn from it. Every creator has strengths and weaknesses, so look for what they do well compared to what you do well. It's not unusual to be better at a creator around your level in some aspects, but for them to be better than you at others.

And if you're still struggling, you can always ask for reviews!

Nothing bad with wanting it to be the best
I think the judgement becomes a bit more natural with time, in all honesty, unless you have real troubles with disliking your work/thinking you are the best of the best already.
Big agree with @darthmongoose, analysing is your best friend. The main goal is to compare and try to be as objective as possible, without guilt tripping yourself. What am I doing well? Am I doing it as well as I want it to be? What can I do better, comparing to this creator and this creator?
Asking for a review is great if you can. I think I only started being better in this after a few years of intensive drawing, but if you want to do it faster, a review might help a lot.

Aaaah.... now that's something that's really hard to judge, but if it makes you feel better, I think anyone who realises that panelling, and choosing what goes in a panel, is one of the hardest parts, and realises it's an area that needs a lot of learning, development and work, has the makings of a truly great comicker.

Really with that one, just keep going, and keep reading and studying great comics. I found the work of creators like Bryan Lee O'Malley (Scott Pilgrim) and Kiyohiko Azuma (Yotsuba&!) hugely helpful to study, because their panel choices and timing are top-notch. Over time, you'll start to really get a feel for that rhythm where the visual storytelling across the panels just works.

Not art, but writing. Had a really OCD person on my back when I was a teen and that critiqued the HELL out of me. I then met some people later down the line, but it was really difficult figuring out which person to listen to.... so I listen to them all and compare their opinions. Whatever opinions line-up I know for sure.

I feel like it becomes a leap of faith doing your own thing without beta readers. You'll still get criticisms sure, but there's got to be a point where you can't rely on beta readers too much.

I studied comics by making a list of DC/Marvel comics through the ages (I'm in the 80's). Not just dialogue, but camera angles and how panels evolved over the ages. I can share you a list if you'd like. (Speaking of DC I refined my scripting skills by taking their format after I entered their Milestone competition).

First of all I have to agree that paneling is the worst thing ever (I, for example, have this problem when I get lost in this whole 180° thing and I can never choose an angle because my mind is just being thrown around through the whole scene, ugh).
Second, if you would like to participate in community and maybe find some like-minded people to just randomly ask them about art, I will leave the link to sketch a day thread1 here, maybe you'll want to join if you need an advice here and there ^^ no deep reviews there (unless you ask for one?), but if maybe you need a company to share with

@Kelheor
I think personally when it comes to paneling (the 180 rule thing you're talking about), it's a wise move to opt for readability and flow.
Meaning having consistently directed shots in the way the comic is read. If your page is full of panels it's probably wise to have all the characters facing the direction of the next panel. Yes that can limit variety, but it does cut down on trying to load in all sorts of perspective shots and it's easier to keep your designs consistent.
This is something I've been working on recently after reading some Tintin books by Hergé. I've noticed the more I change angles/directions on a page, the harder it is to shift my eyes to the next panel. And the same is true when I read other comics.
Of course that doesn't really quite apply with vertical scroll, I don't know much about that type of layout unfortunately.

Okay, to add my two cents in to the overall discussion...
I believe that comparison is an important thing, but mainly in a way that is constructive. If you see something you like in another comic, compare how they would do it to how you would do it, and try the technique out in your own way.

Secondly, I suggest reading a lot of comics. Read manga, read American comics, read European comics, read Webtoons. I spend a lot of time reading professional comics, because I get more value in my comparison efforts. Work on getting that critical eye developed.
I probably spend at least 30 minutes every day reading comics in some form or another. And it's very important to look at different styles, even if it might not be your jam. If you're trying to learn anyways, rather than just being entertained.

Don't really have anything to add that hasn't been said unfortunately - it's still hard for me to apply what I learn analyzing panels and coloring because so much feels part of the artist and doesn't feel mine when I try.

That said, I do have a good thread for paneling because studying regular cinematography helps a LOT with it - it's about shot framing in a 3D Animation, but a lot of principles carry over. Honestly sometimes it's easier for me to study animation than comics;;

https://twitter.com/brendandjcad/status/1661837220741783558?s=201

To see how well your comic is doing I would suggest looking at your statistics. How many views you get per episode, like per view ratio, recurring readers, etc.

Statistics is what helps you analize how well recieved your comic/story is. A good independent author usually has similar proportional statistics to a story that tapas got the license to. By proportional I mean they usually have the same like to view ratio. Or subscriber to view ratio. Proportionally the same amount of positive and negative comments all of that.

View wise you probably can't compare since tapas gives way more promotion to works they get the license. You also have to take into cpnsideration how many views your last few chapters generate. If your views have dropped from 3k per chapter to 100 that means your story is not as successful as tapas may make it look like. What do I mean?

Tapas views of a series stack over all chapters. A series with 1k episodes may have 300k views. But that is basically saying your series has 300 views per chapter. So it may not be good compared to a series that could have 100 episodes with lets say 50k views. That would give you an average of 500 views per chapter.

As you can see even if the smaller series has less views proportionally they would be doing better. Both scenarios have a good view ratio but they were only used as an example to show that it is not as simple as looking at overall views or likes since tapas stacks them.

At any rate if you want to see how well your series is doing you should look at it from a statistical point of view. You should always try to improve said statistics by asking yourself who is your target audience and who your current audience is and what attracted them to you in the first place.

Make lists.
Take 10 comic books that you like and write down one thing that you
think is really good about it.
Then write down what you don´t like about it.
Make the same about your comics. Compare it.

You will see that you are worse and better at things than some artists.
All of those dudes made artistic decisions and have their limits, some are
very limited

What are the things on your list which are really important for your stories?
There are things you are good at and there are things you need to improve on
to make your comic look better. Every artists goes to those decisions.
The people you look up to have their limits and made those decisions too

1. Accept that there are million creators better than you are in one way or another.

2. Accept that you are better than a million creators in one way or another.

3. Stop ranking and focus on making the best possible version of the comic you want to make. You're wasting what little time you have on the planet otherwise.