I've been a player in a 4e campaign since the release of the edition... but I can't keep playing 4e
Good for you - you should absolutely play the game that appeals to you, and not play a game you don't enjoy.
(I myself abandoned 4e pretty early on - we only played a single test session. Although we did promise ourselves we'd give it another go if and when we could recruit two more players (to bring the group to the recommended 5 PCs).)
The rules are in the background.
I must say I'm surprised by this - I find that the 3e rules are quite intrusive indeed, especially when compared to rules-lite games. I had thought the more rules-heavy a game was, the more intrusive those rules, and 3e is definately seemed more rules-heavy than 4e to me.
This would be a taste issue, rather than an inherent flaw in the system. Remember, just because 4e isn't for you doesn't make it a bad game.
4e has a very artificial feel. The labels/roles are a big part of that; striker, artillery, leader, minion ... where is the mystery and wonder?
I would have thought you should be able to ignore the roles for the most part. PC roles are intended as an aide for creating characters and parties (what sort of character do you want to play? Okay, try one of these classes. Want something that will fit in the group as a whole? Well, get one of each type first, and go from there.) Similarly, the monster roles are an aide to the DM for encounter design.
Once you're actually in-game, the roles never ever need to be mentioned, or even considered.
Also, do you seriously expect to get "mystery and wonder" from your choice of character class? Surely that's something that should be coming from the in-game experience - from fighting terrible monsters, recovering wondrous treasures, and solving eternal mysteries?
For these reasons, I'm starting a pathfinder campaign.
Good choice. Though you might also consider looking to other options. I can state with confidence that Star Wars Saga Edition is a great game, as is the 2nd Edition of Warhammer Fantasy Roleplay. Or perhaps Mutants & Masterminds might suit?
Ultimately, find what works for you, and have fun with it.