on your list, i have driven the Z4, S2000, MR2, Boxster and S40. i cannot comment on the others.

the best drive IMO is the Boxster, with the S2000 a very close second

the SL500 might beat all of them but it costs 2-3 times as much.

Hyundai has never made a good driving car - i don't expect the V6 coupe to suddenly start beating out the others.

the S40 will be all the way on the bottom, but it's a family car. why not compare it to a VW Passat or Lexus ES330?