For those with experience in the following games, how would you rate or summarize high level play in each?
D&D 3.0
D&D 3.5
Pathfinder 1E
D&D 4E
D&D 5E
Pathfinder 2E
LevelUp A5E
I have only ever played a level 1 Pathfinder one-shot at a convention. Never played Pathfinder again. I enjoyed D&D just fine.
I have played in lots of games, but will touch on only the High level stuff.
3.5 - Natural progression Level 20 Eberron game was lots of fun. The one problem later in the game was the power-gamer/deep-roleplayer in the group. He played a Warlock, but got tired of it and respec'd into Psion (I later found out he discovered some busted RAW psion combos he wanted to powergame at high level). It was frustrating for both him and myself.
3.5 - Played in a 30th level adventure campaign (create our characters at L30) using the 3.0 Epic Level Handbook. The DM was the aforementioned power-gamer of our group and no one else wanted to run Epic, so he volunteered. He wanted us to make Epic spells and magic items because he wanted to do that for his bad guys like they were his characters. It was him showing off his awesome builds. Absolutely terrible experience and after several sessions, people bailed.
4E - I DM'd an FR campaign to level 30, embedding people's Epic Destinies. The story was wonderful (people cried at the end), but some of the Epic combats took three 3-hour evening sessions to get through. I was ready for a change after the hyper-inflated numbers of 4E.
5E - I DM'd two side-by-side campaigns for a homebrew world to level 20, and the heroes from both tables saved the world. 5E has consistently provided my favorite mechanical high-level experiences ever. One group almost killed Asmodeus, but it ended up a draw. They still technically won and most of them became Gods for the new world.
5E - I DM'd the next generation of heroes for that the last 5E campaign, where the campaign goes multiversal. Got to level 18 before we got to a natural long downtime, and another player wanted to run something (that is what we are playing now, and we're level 9, and he chose our shared campaign setting for this game). The characters are still alive and we may return to them for an Epic romp to wrap up some Epic Destinies.