both are great but would go with the R230 early 2000s SL gets my vote for the electric hard roof. 2 cars in 1.
As a Mercedes owner I do have to say maintenance isn't cheap on these cars and shocks and suspension (ABC and the problematic Airmatic) is a pain to maintain. Quality of interior switches went down in the 2000s compared to the over engineered cars of the 80s and early 90s. Alot of plastic in the lower option models.
A good alternative is a Porsche 996 Cabriolet with a manual gearbox from 98/99, the earlier the better with little to no options. Very fun and rewarding car for the price.