If you're buying a new one, whatever fits your budget and is compatible with Lineage/Graphene.

The only times I've personally been forced off of a Samsung phone (though I've mostly had flagships) wasn't due to any day-to-day degradation in user experience. It was stuff like switching USA carriers or my carrier blacklisting devices with 3g. My current S22 Ultra is three years old, going on four, and aside from needing to use adb and shizuku to have a semblance of control I once had with root there's nothing wrong with it. My previous phone was only replaced because it became incompatible with my ATT phone service in the US. The Note 9, which was four years-ish old when ATT decided 3g+4g wasn't good enough and deactivated any SIM i put in the thing. If not for that arbitrary carrier-made decision, I can't think of many things that 9 couldn't do that the S22U can.

My next phone won't be a purchase I make until I absolutely need to make it, and at that point it'll exclusively be a pick from degooglable unlockable models. I'll probably choose based on hardware like an SD slot, removable battery, and stylus if any of those are available. Or maybe linux phones will be a thing at that point and I'll be looking at those.