Having owned both a 500E and C36 (and driven a couple of C43's) my nutshell is that they are different animals. Which is better depends heavily on what you find most appealing/important. In order of age:

The 500E/E500:
The car is heavy and it is evident in its handling feel. Though it can outhandle many cars designed solely for corner-conquering don't expect the feel of a Miata. Tossable is not something that comes to mind. Gas mileage and tire wear are the side effects of gonzo power and high curb weight. In hot climates with aggressive use high engine temp can be a problem but only under the most extreme conditions. That is about it for "down side". Everything else is upside. Power...it hits about as hard as the C43 does at its best off the line but when that V8 hits about 3500rpm and the valve timing kicks in it will destroy a C-AMG no problem. (no matter what RPM the C is at) From any highway speed the 500E is nearly untouchable. They are super "tight" after 100K+ miles which cannot be said of W202 AMG cars. The paint, interior fit/finish, and whatnot are leagues ahead of the W202's. By the numbers...handling 8.0 (on stock tires)8.5-9.0 on 17"s, brakes 8.0-9.0 depending on aluminum calipers vs 600SL ware, power 9.5, build quality 9.5. One other thing to consider is that a W202 AMG will depreciate more than any 500E/E500 will simply because it is newer and depreciating quicker all things being equal. In my opinion, all things are not equal and the 500E will ALWAYS be more of a classic than the C43/36's.

The C43:
This car is much lighter and has a more nimble handling feel. Though the raw numbers may not be much different (especially if the 500E has 17"s) the impression is of a smaller/lighter more tossable car. Handling is also more gradual/forgiving on the AMG's. The C43 leaps off the line hard but does not pull comparably after that. Its brakes will have the most bite of just about any MB available but that becomes more tire limited given the brakes huge potential. (read: buy good rubber!) The C cars will have more modern options (HID headlights, 5-speed tranny, etc) but the build quality is nowhere near the older cars in my experience. Not just the materials used... Rating by the numbers...handling 8.5, brakes 9.5, power 8.5-9.0, build quality 7.0. The C's are more nimble, scoot nicely off the line, and are more modern.

Final thoughts...the power from the 500E is just plain seductive/intoxicating. The handbuilt nature of the 500E is also a big plus. They eat gas, tires, and about anything on the highway. With better tires and some very minor tweaks they can match (or beat as our Shop Forum members have tested) the E55. That alone is noteworthy but I'm sure the same debate arose between 6.3 and 6.9 owners decades ago. The C43 will be more modern and have a lighter handling feel. They "feel" just as powerful as the 500E due to how they step off the line but under the test gear (read: GTech) the 500E's are just plain faster. If all of your driving is in tight stop/go traffic you might be better served by a C43. If you have lots of highway miles, the 500E is the ultimate stock benz. Having had both, in retrospect the C-AMG's are fun but there is something about the 500E that captures your heart. Styling I leave up to your own opinion but its one of those classic vs new/modern issues. Bottom line....drive both and see which one of these fine machines presses your buttons the best. If you can't decide I'll sell you my C36 and get another 500E.

Guess that casts my vote...Lee