Here is a quick list of RPGs you should try if you like D&D (any version, Pathfinder included) but want to play something different:
- Dragon Age/Fantasy Age: the fantasy rules system developed by Green Ronin for the tabletop version of the Dragon Age RPG is fast, easy and pretty similar to D&D. It uses 3d6 instead of 1d20 and awards ‘stunts’ when you roll doubles.
- Conan 2d20: Modiphius developed the 2d20 game system and has adapted it to a lot of different settings. Conan is iconic and as detailed as you can dream of. Worth your time.
- Dungeon Crawl Classics: quirky old school game system, based on classic D&D with the addition of some more dice (d30). The Lankhmar setting for DCC is a masterpiece.
- Warhammer Fantasy: I liked the 2nd edition a lot more, but the new one has a good art value anyway. Zweihander, a remake of the classic WFRPG, is also good.
- Numenera: it plays like D&D but all die rolls are made by the DM. Its basic setting is Earth so far in the future that magic is no longer distinguishible from technology.
- Advanced Fighting Fantasy: a classic-era RPG, based on the system which powered the old times game books. The setting is fantastic, the 2d6 system is as easy as you can get.
- D&D 4: nothing to do with other editions of the game, but a solid fantasy combat simulator.
I guess you can start with these. The Largest RPG Download Store! is the best place to buy pdf or print on demand games.