i've been in taiwan for a few years now, and just started to pay attention to the hsimen (ximen) and zhong xiao dun hua areas. Before, i just frequented x-large and shops by Gong Guan, but now have visited most of the spots listed on this forum. I'm more of a shoe person and looking for supreme, x,-lrg,and stussy shirts. Taiwan does raffle tickets at most shops. where you pick those up in the morning and come back at 2pm or so for the drawing for the item (hats, shoes, etc.) AF! low white/white are limited over here for some reason, and many kids line up for those they same way they do for a subcrew hat. Alright here are my frequent visited areas with some advice:
Wowtogo by ShiDa is a nice spot for authentic stussy and they got their own brand and pottage bags, just opened a store in Zhong Xiao with the bags.
All the other shops in ShiDa are fakes, like the tyson, tera patrick, fake, and bape brands. You can tell by the tags, print quality and made in thailand tags inside the shirts. Most of those come from Wu Fen Pu btw.
Gong Guan has a few small shops that carry legit stussy and Nike Sb's.
As for the Zhong Xiao Area, X-large, Leftfoot, Under-cover, Under-peace, Bape and everything else on the map are nice spots to hit up. But be ready to shell out the dough. X-large has friend's and family sales, but got to be there at the right time to get the good stuff. (btw X-large just opened a shop in Taichung had a logo shirt with the taiwan flag in the background.)
Ximen is the hipsters paradise. Unity, Apery are a block away from the area. Shock Value is behind the movie theatre with some smaller shops, and in the opposite direction there's an alleyway behind billion boys club (lrg) with Remix, Motherf**ker, Overkill, etc.
Maltose across from A chung noodle shop has some SB's. You can check out the malls but they are mostly fakes from the same origins.
Wu Fen Pu is the paradise for girls, but if you want a limited edition print you can get a bunch of fakes and bargain a deal over here. (prints are a little off or blurry at times, but better to get them here then shops elsewhere since they buy them from here in the first place.)
Hope that helps a few looking for shops in Taiwan and what to look out for.