Mercedes: they have some awesome performance cars that come out of AMG, but otherwise, nowadays they're overpriced chick-cars for pompous people who aren't actually into cars.
Audi: All the S cars (S4, S5, S6, S8) are awesome, but the average ones are pretty blah to me. I used to work for VWOA, and can tell you: Audis are pretty unreliable. They have a lot of electrical issues. I've driven basically ever model of Audi brought to the US from 97-07, and some of them are great but most are pretty dull to drive... way too heavy.
Acura: The NSX is a phenomenal car, the Integra and RSX are some of the best-performing FWD cars in the US, but their luxury sedans are subpar when compared with Lexus, Infiniti, BMW, and Mercedes. They aren't styled very well (the TL is just plain WTF and the RL looks like a Hyundai; their SUV's look like Audi knockoffs) and the way they drive isn't up to par with the big boys.
Nissan: they have some cars that are spot-on such as the Skyline GTR, 300ZX, 350ZX, Silvia, etc. but then they have some complete duds: the welfare mom-special Altima, the fast but impossibly dull Maxima, the absolutely hideous Pathfinder, Pathfinder Armada, and Frontier.
