what you use for developing games and why?
I'm using Java with LWJGL. I made my own engine (well, 80% my own, 20% borrowed for sound and miscellaneous other stuff). I'm a nerd and particularly enjoy learning how to program graphical and networking components. I use Java because it's what I know, and I've learned the hard way (i.e., wasting time) that it's as good as anything else out there for making games (particularly with the very well supported LWJGL library).
Do I recommend that you do what I did? Only if your goal is to learn all the low level junk. Otherwise, absolutely not! Pick an existing engine that meets your design goals and needs, then go from there. Kapta and H3ckboy listed some really nice options for you.