hmm... Well, its a close tie between Nova and Overide, but i'm gonna have to go with Nova on this one.
In story they tie in my opinion. In terms of quality I love them both, Overide has the advantage of being able to do more than one without changing your ship, but Nova Strings are much easier to get into and less frustrating.
Graphics werent much of an issue, as I'm using Cold Fusion which basically makes Overide look alot like Nova.
Overide pulls ahead in the money department for a few reasons. 1: Theres no rediculious Earth-Europa run. There are a few trade routes that are similar, but nothing nearly as rediculious. 2: The Story missions actually make you quite alot of money, and you can actually buy and upgrade a good ship without abusing trade runs.
However, Nova wins simply in game balance. Lets face it, missles SUCK in Overide. They take up a ton of room and arent really that good. In Nova theres a good balance between Cannons and Missles in my opinion, not to mention there are way more ships.
Also, I like how the Nova pirates actually act like pirates by boarding you and taking your sh*t rather than simply blowing you out of the water