Im wondering what kind of tv to look for?
IMO 4k is useless because the network where I live is bad and 1080p is good enough. I don’t think smart tv functionality is a thing to look for, more like a « what not to look for » criteria.
What other criterions should be taken?
4k useless? Are you living in 2007?
Depending on the size of the screen and the sitting distance, sometimes 1080p is more than enough.