I like both sites well enough, as it's nice to have hosting sites available to use at all!
My preferences skew towards Tapas a little bit, as it has some creator-friendly features that are just completely absent on webtoons. The dashboard has more information here than there, Author Notes can be much longer, the tipping system exists, the creator wall is nice (although it would be nicer if it extended to the app as well...), notifications for likes and comments, etc. I've just recently started hanging around again since taking a several month break between finishing my last comic and starting the front-end work on a new one and aren't a huge fan of some of the layout changes they've made recently but... eh. Multtiple genres and covers are a thing now so that's pretty rad!
Re: Webtoons is nice because of the larger audience though. My first comic actually performed better on Tapas than Webtoons consistently throughout it's run but I've heard enough anecdotal evidence to get the feel that that's not the norm. Further whenever I mention webcomics to people irl (friends mostly, but sometimes randos too) anyone who's savvy with them mostly all know webtoons but a lot of people haven't heard of Tapas... which is understandable. But that means it's nice to upload on Webtoons as well so that you can more often than not direct people to your comic if they only read on that platform.