I am speaking from personal experience so SLR would probably be on this list otherwise.

Favorites:

pre 1991:

1971 300SEL 6.3

post 1991:

my C36 TT and 500E (can't have just one)

Dislike:

pre 1991:

1976 circa 300D non turbo or 240 if they made one

post 1991:

ML 320, C230 hatchback both with the obligatory cloth seats and roll up by hand windows if available