I'd say go with a C5. Going to have good handling with a little amount of money thrown into the suspension, same with speed, parts for C5's aren't cheap however. Shit, they are fun in stock form. I would rock a C5 Z in a heartbeat. Or try and find one that was already built, but that's just me. I love Porsche's but to me the cheaper ones aren't as fun for what you pay, they handle well, but I'm a big guy, a Porsche just seems too small in my eyes, most models in that price range I would assume.
DSM..never owned one, but all my die-hard DSM friends hate the reliability issue...
But just my 2 cents.