this depends entirely on what you're optimizing for, but i reliably find way too many things i like on svaha
their stuff is well made, they have lots of fun patterns, their skirts and dresses have pockets, it's easy to find things that fit me
they are not great if you're on a budget, but if you're on a budget then thrifting is probably a better way to go than online shopping
ive found a few things i really like on modcloth
and ofc there's always sock dreams
i also know some people like black milk; i haven't had as much luck with them myself
this is dated at this point but this is where i started exploring alt fashion
also, it's not on this list, but most of my favorite clothes come from Mary Wyatt (just google it)
if you're a fat bitch like me,
eshakti does customized-to-measurement alterations for a small fee and often has sales. tends towards more like.......straight girl than i prefer but sometimes it's got useful items
torrid used to be much better but it still often has cool shit and it's really been the only place i can find good underwear and jeans in my size (though almost never in quite the length i require, but that's almost nowhere)