Hmm, difficult question... All?
'79 XLS1000, not a bad ride although it was HD with its typical 'issues' but that just gave it a personality of its own. V-twins are always cool.
'85 VF1100S, the sweet & peerless V4. That heavy hunk 'o metal would sure fly. Well mannered and easy to get along with.
'06 Ducati monster 620D, a street bound dirt bike. As good a dance partner as there ever was. Nothing else handles the curves as such.
'06 FJR1300A (I still have this one, does that count?) The big gal is still a passion, and she has been very well appointed. I do resist putting this one up for sale. Depends on the budget, but desperate times can call for desperate measures. :-\
As for the dirty bikes, a '76 DT 400 comes to mind. That has been quite a few moons ago.