I think for me, one part is it is a story only I can tell the way I want to tell it, and there are certain elements that make it unique because they're put together the way they are. Looking at them singularly makes it not very special but the way they are put together plus how my art just is makes it one-of-a-kind in some way. Are there fantasy universes? Plenty. Is there a lot of drama surrounding royalty? Heck yes. Lost prince and dead parents trope? Pretty much. Romance? More than I can count. Characters not knowing where to go with their lives? Uhh yes. Excellently executed crime mysteries? Definitely more and better ones than what I am doing.
But the fact that my "fantasy realm" has literally as much magic as our world we live in right now and it stars a lot of queer POC it starts getting more unique because those things aren't featured that often. I think you don't need to think about "what makes it better than the others?" (who has the better potato, as you phrased it) but to think about "what makes it unique?" because more often than not that's the selling point eventually. It doesn't even have to be a very unique idea but the way you tell or depict it already makes it unique on its own.
And more than anything else, does it bring you joy? I personally get ridiculously excited and literally vibrate on the inside whenever I think of my comic because I just want to tell that story (and I love my character/costume designs so much and really want to show off all the world-building.) There is always a reason why you started, and ultimately, this should be the reason to keep going. Even if it's just a practice comic, the reason was to practice how comics work and maybe try something new.
Try to be enough for yourself. You don't need to be the best, just be enough, that's okay.
Also, try to see other people's art as encouragement to just make better next time, try to see what they're doing and maybe just test it out for yourself in a way that you think works for you, it can be real fun and sometimes opens the way to new techniques that help you incredibly much on a daily basis. Draw inspiration from it instead of putting yourself down.
A lot of people struggle with this, so you're definitely not alone and personally, I am still working on some aspects of this as well. Much love, you've got this!