I have had lots of Corvettes and they are what they are... best in class value. Bring a cannon to a knife fight. Dealer network sucks relative to the price of the car... you take it to the same place that services 12 thousand dollar Chevy Sparks so you can imagine. Enthusiast support network is off the charts though... you can post on one of the corvette forums and get more feedback and help than you can imagine.
As to Infiniti... peppy yes. My Wife drives one. I don't recommend. Dealer network is up and down. Some are great, some will screw you. It's still just a nissan with leather. None of the controls are really configured for a left hand drive vehicle, including things like the windshield wipers that stop right in front of the driver's face. It's like they do the conversion from RHD to LHD to the bare minimum. I will give props to the reliability. So far we haven't had any issues. Literally none. Every new car I have ever had has something to get fixed under warranty except this one.
Mercedes is 1st class ride and luxury. Dealers are required to be the best, and in my experience are.
Caddy ATS V or CTS V. Down side is dealer network is like Infiniti... some good, some suck. Plus side is a great support network and american parts network for the long run.
Jag you will likely regret. Best looking of the bunch though. Exhaust sounds great too (like the 'vette) and there aren't many on the roads. Dealer network is practically non existent. Non existent support network over here in the aftermarket. The jag is a lease and turn in car if you have a local dealer that isn't far from your house.
The whole BMW line is about driving... I drove the new 4 series coupe for a couple days and it's nice as heck too. It's performance / driving oriented Vs. the Mercedes luxury oriented. The BMW is a finely tuned machine. Costs more than a Vette, not as fast if you know what you are doing (professional driver or have a TON of experience)... faster if you don't know what you are doing (basically almost everyone). Dealer network is like Mercedes. Best of the best.
My BMW M3 is a 2011 and has about 22k miles. I daily drive a 2013 Chevy Volt which is the best car I have ever owned. It has nearly the same miles on it as the M3 despite being 3.5 years newer (volt was a leftover) If you can find a Caddy ELR to test drive I strongly suggest it. The ELR is a nicer version of the Volt and I recently found one new for 30k off sticker. My Volt has plenty of power, costs practically nothing to operate, ultra quiet, and actually quite fun to drive because the center of gravity and weight. It drives like a really heavy European car. plus that 7500 tax credit was more than welcome.
I agree cars are meant to be driven... I have a Corvette with 100k on the clock. But when you drive a car like these (M3, CTS V, Vette, etc.) daily you can expect to not be happy 100 percent of the time. That's why I drive the BMW sometimes and the Volt most of the time (and at this point the 'vette is at my wife's parents and they are driving it for now... I clearly have too many cars). Took the Bimmer to work today, taking the Volt after work down to Disney with the family.