Horses for courses: Which "trim level" and what are you going to use it for? How important is acceleration vs fuel economy? Is styling important? Back seat room? You can always check out a lot of different opinions
here. These are someof the most reviewed cars around.
I get to drive the Impala SS soon. The V8 seems like it might be a bit much for this car iwth the fwd but we'll see. I have driven the Montego, the Mercury version of the Five Hundred, and it's a competent if unexciting ride. And the Charger really depends on which engine you get. Particularly with the R/T, I recomment the performance suspension. It's not all that firm, and in my opinion, the standard suspension is too floaty, especially for something that calls itself an "R/T."
The Charger isn't available iwth all-wheel drive; rwd only. The /Five Hundred/Montego is fwd, awd optional. The Impala is fwd only. You night also add to your list the Pontiac G6, especially if you would rather have a coupe. Yep, two doors on the G6. The GT falls short of the name, but I'm looking forward to driving the GXP soon. And if you're a "domestic move-up," the Lincoln Zephyr is available, though it's not really a competitor with these cars but a step or two up.
And if you want to go import nameplate (many American made), the list gets considerably longer.
More opinions, road tests, etc at the link above, though.