I really enjoyed FC3 at first. But I lost interest when I realized the enemy AI was dumbed down compared to FC2. I also really dislike how they changed the save system.
As much as I enjoyed FC3, it's still nowhere near as good as FC2. But it's hard to compare the two games since they're so completely different. It's strange to think of these games as being part of a "series" since they're not really at all. All they have in common is that they're open-world FPS's set in non-Western locales.
FC2 really? O yuckers, FC3 IMO was WAY better than FC2, the enemies re-spawn in FC2 was enough to shelf the game for good.
FC2 has its quirks, to be sure, but it takes many more risks in its design and mechanics all around. I'd choose an interesting, risk-taking game with rough edges over a polished, safe game any day of the week.