Save up?
It's not like this fall is unique in the sense that it has a lot of good games coming out. Only having enough dosh for 1 game seems a bit silly when you could see yourself wanting more.
Already blew my fall games budget. I was never planning on getting BF3, but the point still stands. You need to prioritize. I bought three big-name titles this fall (already pre-ordered and paid for); Skyrim, Saints Row: The Third, and Batman: Arkham City. I can't buy every game I want, so I needed to figure out what games I couldn't go without playing and buy those first. I snatched up RO2 with the bit of extra cash I had left over.
Sounds like OP is basically doing the same thing to me. From which of the two titles would he get the most out of his limited funds?