It depends on your skill level, playing style, how you swing, etc. We need more info before we can even begin to make any recommendations. Tell us what you're currently using, what you like about it, ways in which you hope your next racket is better.
Example: I'm kind of an all court player, but I guess I spend more time on the baseline. I hit pretty flat, I want more spin. I don't want a heavy racket and nothing to stiff because my elbow is starting to hurt. I'm using a Pro Staff 6.0 right now and it's just too much. I want a bigger racket face and a more open string patter. blah blah blah