Mob Psycho 100 actually had some pretty clever composition in some areas...
https://www.mangareader.net/mob-psycho-100/17/3
Like this is a pretty good visual representation of Teruki's world shattering while he's fighting mob. Notice how the outlines in the shattered glass on the last panel are similar outlines of the people in the first 3 panels.
I need to reread this manga lol.
https://www.mangareader.net/mob-psycho-100/97/7
Also I gotta give ONE some props here. There are still some issues but he has actually improved his artwork over the course of the manga.
Also to @Riza_Creator
To answer the question, I think that what matters in a webcomic (or a comic in general) the most is the story and how you tell it. I'm talking like composition, how you layout the panels and stuff like that. @punkarsenic keeps mentioning Understanding Comics so that's a good read. But I also recommend studying how other authors handle this. Akira Toriyama is one of the best at this if you ask me when it comes to flow in a panel.
(if you want more on this there's a channel called Strip Panel Naked on youtube)
Art is important for a first impression since that can change over time and you will improve over the course of the story.
Also for a less extreme example on story>art (sorta) I'll point you to JoJo's Bizzare adventure
The manga looks like this right now.
If ONE can do it, you can do it. If Araki can do it, you can do it (also his book on making manga is a good read)
Anyway point is, Story (and everything having to do with it) is a little bit more important than the art. Don't forget about those characters too.