I'd love to be able to get personalized recommendations by genre, myself. Or, a more in depth tagging system would be fantastic, so that you can hunt through really specific tags to get what you want.
An "undiscovered" section would be amazing. If you could submit your work for a weekly "new/unknown artist" feature and be featured for a week or so that could be useful.
Looks like tapas mostly wants to plug their premium comics most of the time though, which personally aren't really my cup of tea (I actually hate most of it don't get me started -) but it seems enough people like them for it to be good business. It doesn't make them any money to plug new artists, they seem to make their coin on selling episodes of the premium stuff, which is disappointing as a new creator.
Now that tumblr's a wasteland, there's not many places for people to post their comics (I guess there's webtoons?). Tapas' UI has the advantage of being slick, there's loads of people on here, and I love their forums, so here I am!