I recently said goodbye to my s205 c63s after 3 years. Simply an incredible machine in every way. All the tech worked flawlessly (apart from the parking assist which I couldn't get to work a single time in 3 years but the 360 cam rendered it redundant). I did many sessions in my mate's rs4 from 2018 and the rs4 is super quick but the c63s is super comical in how it slides around and constantly entertains. Completely different driving experience. The audi can thrill you with gravity defying speed. The AMG is a car you do have to respect a lot or it nips back. But after driving it for a while you do get it to fit like a glove. It sounds immense with the pops and bangs in sport plus, is very fast and thrilling to drive when you push it, and every driver is a sense of theatre. The coupe is the fasted variant probably but the wagon is the most tail happy.
With the C gone, a couple of months later I picked up a w212 e63 s saloon. The e63 feels a bit more grown up, more stable (might be the weight and wheel base and tyre size ?) , the 2018 c transmission was super fast, the e is not quite as quick but good enough. The exhaust on the c was louder (performance exhaust) and can he heard a long way away and is just full of the best drama possible and downshifts are joyous, the 204 and 212 can't compete, on hard pulls, it gives whip crack on upshifts , but the basic revving sound doesn't match the m156 . The tech on the c just works slightly better all round probably as it is a newer platform. The C cabin looks better but the E cabin is probably higher quality and is more roomy. Oddly while driving it, it is the E that feels smaller somehow, the c has these great bonnet humps which help with lane keeping though but something about the E just makes it easier to drive that i can't adequately describe. Oh the parking footbrake on the E is a bit shit, it gets a bit tight and needs the tip of my shoe to pull it up sometimes. The c has an electronic brake which is miles better in that respect and automatically activates when u park the car and turn it off. The engines, well the 4.0 is higher revving but the 5.5 doesn't need high revs

. That 5.5 hits you with an absolute mountain of torque , it is a beast
The E gets a lot more attention than my C did except the noise levels of the exhaust. I get people compliment the E sometimes randomly as I'm driving by (weird because it looks like a taxi to me ) , the C is very understated and I wish it was more in your face. If I kept my C I would have installed an aftermarket wing and front fender bits to jazz it up . The E looks a bit more masculine from the rear and the c estate is a bit roundy but still okay I suppose. Neither are a patch on the way the rs6 looks but I would never buy an RS6 released so far when the E class exists. The E nails it where it matters.
The only way to work out which is better for you is to test drive both. If you live down south I'll happily take you for a spin in the E and you can see what that car is about.
Would I buy an Ew212 s or a C63s , damn its a tough choice and space and a bit more comfort with the rear air suspension currently gives the edge to the E but if i wanted more entertainment from every drive then I don't know , the C is a little bit naughtier it has to be said, but the engine on the E is an absolute sledgehammer. I can't pick a winner and I'd be happy with both...
By the way , there are currently 2 x s212 s AMG wagons on the market with less than 20k miles... that's quite rare...