These are my favorites:
Of course the E46 330cic 6-speed sport started rusting rapidly, so I was forced to unload that.
The 03 E39 540i (true) M-sport 6-speed will always be with me. I keep it in showroom condition; have not quite driven anything that compromises so little comparatively. Lots of sentimental value as well over the years.
(Next to my buddy's E24)
I am however gearing up for the next-generation M3... something tells me that it will be a gem.