I think I mentioned it before, but I prefer when bands do costumes or makeup or something visual with their act, and it makes them less interesting if they don’t. Sure, the music can be great, but it would have to be something extraordinary for me to bother watching a live performance of some normies in shirts and jeans.
But now that I’m exploring asian metal, I’m starting to develop another bias: against singing in English. When I check out a band like this, I’d prefer them to have something that makes them different from western metal. It can be instrumentation (which is why I like folk metal), but the most straightforward and obvious thing would be singing in their native language. Like, what was the point of me digging up some Vietnamese metalcore band if I close my eyes and they’re basically indistinguishable from a western one? And then I open my eyes, and they’re a bunch of nerds in shirts and jeans. 
Like, come on man. I’m gonna need more than that.
I can still end up liking the band of course, but at this point having English lyrics is pretty much an obstacle that I have to mentally surmount to get there.