I have a fondness for the 280 and 300 SLs. Both have the DOHC inline six and are euros. The 300 is pretty rare in the US. It depends on where you are. If you have to pass emission testing then I would go with the nicest 560 you can afford.

For fuel mileage I think the 280 and the 380 are probably rated the best. My 86 560 gets 17-18 hwy. I don't do much city driving.

Each model has it's pros and cons. A favorite expression here is the most expensive SL you can own is a cheap one.