I would go either with the Acura or the Infiniti. The G coupe is really nice if you like sporty, the Acura TL now has SH-AWD so works great if you go to the mountains skiing etc. I owned an Acura 3.2TL Type S a few years back and loved it! I have owned a Nissan Frontier for the last 7 years and not had a single problem with it. To me that adds to a good ownership experience.
The BMWs are fun but they have recurring issues that require trips to the dealership, after a while it gets old…you ask yourself why you have to deal with this after spending 50k on a car.
Also note that Acura and Infiniti USED to be cheaper than BMW and Mercedes, this is no longer the case..both are now pretty damn expensive as well.