I like Savage Worlds for this; everyone builds their character, there can be a lot of variety, and choices matter, but you can also pretty easily run it seat of your pants. I'd say it covers all your bases. In a lot of ways, I think it has things in common with Star Wars d6... both have very similar design styles, but with Savage worlds being a 1 or 2 die resolution, and d6 tending towards a multiple-d6 dice pool.

Speaking of Star Wars, if you've got the Saga edition, you might also go with my Classless version. Built out of feats and talents, it lets you make the character you want, without the careful juggling of levels to get access to talent trees.