You mentioned speed so I assume you're looking for a sports bike?

As I've said above, any modern Jap 600 will do. You can't buy a bad one really.

GSXR600, R6, CBR600RR and the new ZX6RR are pretty full on and aggressive.

The older ZX6R and the CBR600F are pretty good all rounders but still bloody fast

Go sit on a few and see which you like the feel/look off