I prefer
Nova by default.
Neva always makes me wonder nee-va or neh-va? Same thing with
Nila, neela or nilla? Even with it being pronounced neela when it's written I think nilla thanks to Nilla Wafers. So that leaves only
Nova.
Nova makes me think of Chevy
Nova, one of the most poorly named cars ever. no va = no go in Spanish. Still, I have no confusion on how it's pronounced and I think the name has an overall pleasant sound.