My gap between Webtoons and Tapas is pretty big!
On Tapas I've got 18.9k subs and on Webtoons I have 6.2k. I've had that same number on Webtoons for MONTHS while my Tapas subs grow pretty consistently. My comic started out strong there, and then sometime (seemingly randomly), poof, comments stopped coming and subs stopped coming on Webtoons. It's been so stagnant there that I've reduced the amount of times I update per month by the request of commenters there. It's been wild.
I generally think Tapas is a stronger site to use despite the smaller reader number because I think generally people are more engaged with stories here, more friendly towards sexual and queer content (which is what I make), and the tools we as creators are given are a lot stronger. Of course, Tapas has it's flaws, but I'm much happier with how my comic is presented here than I am with Webtoons, where the quality of my upload is garbled and commenters are way more cut throat.
I would say that traditional format comics like mine do more poorly on Webtoons, but I see plenty of comics with my format and similar quality do SO much better there than my comic is and it's just... very strange. Webtoons is a nut I can't crack, similar to Instagram. Both are very odd places to me.
All I know is I'm glad at least people have a choice of platforms? I honestly wish we had more, I wish people would talk about Comicfury as an option more cuz I've used it for years and like it a lot! It's a great Smackjeeves replacement and allows you to do custom HTML, highly recommend it as a mirror site. (They also don't censor you nearly as much as Tapas or Webtoons does.)
In general, growing a comic is really tough on any site and what I've found works for me is to try and do guest comic / comic trades with folks with similar comics to mine. So, for example, your comic has mermaids in it? Do a trade with someone who has mermaids in their comic too-- it's a nice way to cross pollinate your readers and also, it's just fun to make something for a fellow creator and have a bit of fun.
Anyways, my post is way too long and I wish everyone here lots of luck on both Tapas and Webtoons!