Re: 20x9 or 20x10???
I've been debating the same thing and the main difference between x9 and x10 depends on the tires you want. Not all tires are made in the same sizes so, for example, if you're trying to stay as close to stock diameter as possible (to avoid speedo issues, etc.), a BFG KO2 won't fit on a 20x10 rim. They don't recommend anything wider than a 9.5" for a 275/55/20 tire (which is their smallest diameter 20"). If I were you, I'd figure out which tires you want or will be happy with and have that factor into the decision ahead of time.
I'm personally leaning towards getting a 20x10 with a summer tire and then getting dedicated snow tires for my OEM rims. Haven't talked myself into pulling the trigger on anything yet though.
2014 Grand Cherokee Limited - Billet Silver Metallic - Lux II