I test drove the Z4, Audi TT, and Miata, but found the SLK to be the best balance of practicality and fun. I love the way it corners while still eating bumps with the standard Mercedes THUD (this is my 3rd Mercedes). I think it has the best, most organic curves of the contemporary two seaters, plenty of power, firm but comfortable seats, and enough room for two weekend bags. My only gripe - and it's a big one - is the rattles and squeaks. I drove 3 SLKs and they all produced noises over bumps. I think it's a side effect of the hard top.
Security of hard top convertible. Fuel economy (my 225hp 3 litre engine gets 29mpg highway) Sensual curves
Better damping of roof seals, trunk divider, glove box, or whatever else rattles and squeaks over bumps. A car this expensive shouldn't make so much noise. A radio with aux input.