If the question is what previous bike would I want to add back to my stable, it's the R6 hands down. As scary as it was, it was still a fun ride, and the noise coming from the Yoshimura was incredible.
If the question is to pick just one bike to stick with for good, I don't know that I could do that. Nothing really does everything well. A muscle bike like the HD breakout, I suppose, is a good mix of cruise and excitement, but I wouldn't want it on a long trip. Also probably not that great at carving with it's wide rear tire and weight. R1 makes an amazing noise, looks sexy as all hell and would be awesome to ride. But that bike would be out to kill me at any opportunity, not to mention it's nice to sit up once in a while. I am getting to the age where I kinda want to ride a lazy boy sometimes, so a road/street glide are considerations, but that's ALOT of money to put into two wheels. On the plus side there though, Milwaukee iron tends to hold value well.
In all honesty, If I could afford it, I'd have way too many bikes. No one style or brand will ever scratch every itch.