I've been thinking about this for a while now.
Realistically...
1. 240D 4-speed MINT call it a downgrade if you want but I think the 4-speed is fun.
2. R107 560SL - I really like the classic body style and I long for a convertible. I don't really need a practical car as I don't drive to classes. Walking is fine, healthy, cheap, and I see beautiful things everyday hehehe :p
3. W124 .... basically any W124 would do.. the perfect sedan. Elegant, yet understated. 300D Turbo and 300E 5-speed are my top choices along with the coupe.
4. W210 Turbodiesel (E300) - for very obvious reasons.. refinement + diesel
5. This one borders between realistic and unrealistic... R129 300SL/500SL (early model as they are the most affordable).
6. W126 300SD, 300SDL, or 560SEC! or maybe a 91 350SD/L with rebuilt engine.
Not in order but the convertibles -> 2-doors -> 4-doors is the order.
If I had the cash.. I'd get the R129. Very nice looking roadster.