I'd agree with others that say the W124 with the 4.2 liter V8 would be the best W124 model OVERALL.
That would include the 1992-1993 400E / 1994-1995 E420 (the 400E's have the same 4.2 liter engine as E420's).
1. They all have R134a air-conditioning.
2. You get 90% of the power of the 500E's w/o the premium price tag.
3. There is almost no mileage penalty with the V8 over the 3.0 liter / 3.2 liter 6-cylinder engines.
Most everyone seems to like the updated hood / grill / headlights of the 94-95 models, but I think it's largely over-rated. I actually prefer the earlier grill, but no one will argue that the early headlights are prettier. The early U.S. headlights are ugly and put out little to no light.
You can upgrade the look of 92-93's by installing the Euro lights, adding the clear / yellow corners, and installing the clear / red tail lights.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".