The Altima coupe is not a lot of fun to drive, and to me, looks kind of stupid with the skinny tires on it. Big engine, lots of power in the v6 but can't put it to the ground. The 4 banger is a joke.
The Accord coupe is a very nice, good performing car. There is no contest between the two.
Read this article, it's not just me that has this opinion, of which they are a lot nicer regarding the Altima, but i've driven it and hate it. http://www.motortrend.com/roadtests/coupes/112_0804_fwd_coupe_comparison/index.html