i had a yzf600r for several years. loved that bike. fast, dependable, forgiving, comfortable and fun. i commuted in the city for 3 years on it and took it on several trips from texas to Missouri and back (arkansas is a great state to explore on a sportbike).
the F2-F4 hondas are good too, and lots of parts out there for them on ebay and in junkyards. i've been thinking about picking one up for another track bike just for that reason.