As long as I can hold it in one hand to my ear, and put it in a pocket, bigger is better. With much longer wireless earphone battery life, the former constraint might not apply.

Ultimately, the main use (by time spent) I have for my phone is reading and watching, and therefore the main complaint I have with phones is that they don't have enough screen, and the next biggest is UI lag. The recent folders like the Surface Duo and others have been interesting to watch, but they have so far sacrificed too much in other specs for that gimmick.