If you're talking of mechanical features first, then the W124 would suit you fine.
If you are into electronics and want a sample of how and where MB begin venturing into e-systems in engine management with some refinement in and out, then the W202 would appeal to you.
Comfort wise would be more or less the same, then again, as mentioned earlier, we ARE looking at 2 very different categories of cars with different perspectives tailored in mind. Though they have things in common, the chasis and engines seperate the two. Of course, the W202 runs on a newer designed engine.
At the end of the day, its your desire over preference with whats available in the 2 models.
Now, if I was confronted with:
1. 93 300E 104K miles $10500
2. 91 300E 75K miles $15K
I'd go for the cheaper as I believe that miles for that age don't matter that much, more so when its a difference of 30K PROVIDED that the 104 miles meant long distance running and not because of extreme city driving.
That is just MHO.