I've flown the C310, B55 and the Duke. Only the Cessna survived.
B55: Nice graphics, good flight dynamics, pretty good handbook. Fps are not so good. I don't like the instruments so much.
The mission pack (http://milviz.com/filesfordownload/missions.zip) is cool!!
Duke: Crisp cockpit, even radar altimeter! Still it feels sterile and synthetic. Fps are not so good either, but I
think its a little better than the B55.
C310: Graphics are not that much state of the art - after all its a 2010 model. Excellent flight dynamics, very
good handbook, good overall package. G1000 version included, the Mindstar G1000 and flight1 GNS
can be integrated. Also, if you tweak it a little, the B55 mission pack will work on the Cessna too.
Since I like IFR flying and buzzing around at high fps, my choice would be the C310. It's the aircraft I
fly the most in FSX and Milviz even ported it to P3Dv2.