If I had to swap my '12 R1200R for a different bike (and money was no object) it would come down to these four: R1200RT, Triumph Street Triple R, Kawasaki Ninja 1000, and Honda CB1100.
The R1200RT would make for a better second bike than a one-and-only for me, but I sure would love to have one for touring. I wouldn't particualrly want it around town or on my sport rides, though, which is why I opted for the R1200R in the first place: it does it all.
So, as a one-and-only replacement, I would have said that the Honda CB1100 was my first choice...but that was before I owned the R1200 for a decent while. Now that I have in fact had it for about seven months, I'm not sure that I would be satisfied overall with the laid-back Honda. I suspect that in comparison to the BMW it simply gives up too much in terms of performance.
The Triumph? I passed on it when I bought the BMW for the same reason I would probably pass on it now: too narrowly focused. Just as the R1200RT would be a bit limiting to me, so too would the Street Triple R. It would likely be my first choice for sport riding, but I do too many 400-mile days and long weekend trips. I would miss the convenience of the hard bags, heated grips, and shaft drive.
So, I suppose I would probably look first at the Ninja 1000. The seating position is comfortable enough (for me, anyway) to tour, factory hard bags and heated grips are available, and it has a bit more performance than what I already have.
That being said, I don't think I would trade my R1200R for one. I fear that I would grow out of the big Ninja. I have no similar fears concerning my BMW. I feel like I could own this one forever and it will always remain cool to me.