I am in the market for a super sedan myself and my order of preference is as follows:
1) F10 M5
2) F80 M3 (maybe)
3) Porsche Panny 4S or GTS
4) MB E63 AMG
I like all 3 (except M3 since I cannot actually drive it yet) and the M5 is the best car for the money IMHO. The Panny is the best car overall, but it is underpowered for what it costs and the trunk space is a joke. I am debating picking up an M5 this year or waiting until spring of 2014 to see what the F80 M3 looks like.