I tested the Altima coupe with the V6 and manual transmission a few years ago. Definitely thirsty, and one of the worst-riding cars I've ever tested. My wife hated riding in it. I think the four-cylinder coupe has a more compliant suspension.
The Accord is a larger car, so it doesn't feel as agile but has a roomier back seat and a larger trunk. Both the back seat and the trunk are quite small in the Altima.
I haven't checked prices, but Hondas tend to depreciate more slowly, so an Accord probably costs more than an Altima.
Reliability should be good with either car, though the Accord has an advantage in this area. Transmission replacements are more common with the CVT in the Altima than the conventional automatic transmission in the Accord.
Some people also don't like how the CVT feels in the Altima, as it tends to hold the engine at a constant rpm while accelerating.
If you'd prefer a manual transmission anyway, these CVT issues aren't relevant.