The iPhone 6s continues to be the best piece of hardware I've ever owned. I imagine folks with an SE feel similarly.
faceID is nice but touchID is just fine. 2GB of memory is fine too. and while i don't use the headphone jack much any more, it's nice as a backup for when i forget the airpods. i may upgrade next year with the purported 5G rollout, but i'm not even sure that's worth it. LTE is fast enough and its coverage is mostly good enough too.
Plus, I am pretty confident that the speeds that I actually get didn't change by a huge factor when the transition happened. If anything they got slower because of congestion, due to the amazing price drop and crazy increase in user adoption.
The X and beyond are nice, but I think the facial unlock is a pita and stopped my upgrade. I also ordered a purism phone...