First off, cool. I hope you find the right tool to build your next campaign with. Now with that out of the way...
* The rules are in the background. The rules are not constantly superimposing themselves on my in-game experience. Example: 4e marking.
You didn't feel that all the bookkeeping required by mid-to-high level 3.5e was intrusive? I sure did, then again, I was running a campaign that ended up with 4 full-progression spellcasters. We couldn't avoid a lot rules talk during heated battles.
* High level of player creativity in character design.
Have you tried Mutants and Masterminds 2e for a fantasy campaign? It's a classless point-buy d20 variant (in case you didn't know). Which means it has the most flexible character generation system of any d20 game. Any character you can make using 3.5e/Pathfinder can be made using M&M2e, plus a metric ton of ones that simply can't/won't work under 3.5e.
Plus, the game itself ends up being much easier to run that 3.5e.
...if my first exposure to D&D was 4e I'd probably say to myself after a few sessions, "why not play WoW instead?" IMO, Wizards forgot why people play D&D in the first place.
Heh, our 4e games are nothing like a MMORPG, they're like more like a sloppy blend of Terry Pratchett and China Mieville's novels and Quentin Tarrantino's films, only with a lot of the quality removed.
Also, another way to look at it is that Wizards rightly understood that most of the reasons people play D&D can't be found in the rule books, which explains why they provided a robust set of combat resolution tools, a loose framework for conflict resolution, and basically left the rest to the individuals playing.
For these reasons, I'm starting a pathfinder campaign.
Again, good luck, and have you considered M&M2e? There's a new source book out now for it called Warriors and Warlocks, which is full of advice/fluff for running a pulp fantasy game.