What kind of sports car would you get?

I'm looking for a new car and I want it to be reliable and have a lot of power. I don't like 2 seaters. I know I've asked a lot of car questions lately, but I wanna here other peoples opinions. I'm looking at the mustangs the wrx and the 12 year old mercedes v12 cars. Are there any suggestions in which car will serve me better and for a longer time? Any other cars that you'd recommend?

NONE of the above. First off, you can't afford the insurance on ANY of these vehicles, and you Definitely can't afford to maintain a V-12 Mercedes.

Perhaps you should start looking at something more practical and affordable… Like a 4-door Honda Civic or a KIA Soul.

Corvette

One of the main problems with buying a V12 merc is that even if it costs $15,000, you aren't going to pay $15,000 car levels of maintenance. You will need to pay for the maintenance of a car that was possibly over $100,000 and this is going to be extremely expensive.
my best suggestion is that you look at much newer entry level sports cars.
things like a mazda MX-5, Scion FR-S, Hyundai Genesis Coupe, Ford Mustang v6, Chevrolet Camaro V6 or dodge Challenger V6 all would provide decent levels of performance for a good price and not bad reliability and maintenance costs.
my personal favorite is the Genesis coupe because it combines the lightweight handling of the japanese cars with the power and torque of the americans.
if you still feel like buying a mustang, wrx or v12 merc, i'd suggest you go with the WRX. Subarus are very tough and have amazing reliability records. The WRX will be a very good car especially if you live in an area with winter. The rear seats help out a lot and it won't be as expensive to maintain as a v12 merc.