I started off with a katana 600 and it was a lot of fun, but with the carbs and all, I wanted a more reliable fuel-injected bike, so I picked up an '04 SV650 over the winter for a killer price and started riding early spring. It was my introduction to a great handling aluminum framed bike that goes where you point it. I still think that its a great bike, but the lack of top end power/speed made it not ideal for highway riding for commutes, so after riding it for about 3.5 months, I just picked up an '09 R6. It's night and day and now I can never do back. I was lucky that the bike came modded and has more low-end torque for daily in-town riding, but it was at the expense of some highway top end. The SV is a great touring bike though, if you don't spend too much time on the highway. I definitely don't regret buying it, as it made me a much better rider during the time that I had it.
Despite what some people say, I find the riding position very comfortable on the R6 and can do several hour rides at a time without any soreness or complaints. I think I've almost found my perfect bike. Once my insurance is more affordable (more years of riding experience and bundling my cars and house), I will try an R1, which will have both the low-end torque as well as top-end power without the need for compromise for one or the other and see if that can become my forever bike. or try a Busa! Life is short, gotta try more to see what's the best fit!