I have both games. I can say that they're the best games ever released for the Playstation 3.
But if you have to choose just one, there is no doubt for anyone who actually played both games that Uncharted 2 will be the better investment. There is a reason why Uncharted 2 has a higher aggregated score (
even scoring a perfect 10 amongst 90% of online critics) than Assassin's Creed 2. Uncharted 2 is a thrill-a-minute experience, a fantstic combination of genres that pay homage to the best games for the past 15 years.
Of course, like what Gh0st said, the multiplayer should be the clincher. If you're going to invest P2,395 for a Region 3 copy of Uncharted 2, you'll want it to last a long, long time... and the game's multiplayer mode (which will allow you to level up and gain "perks" just like the Call of Duty series) will keep you busy until next year.
Opening sequence pa lang ng Uncharted 2, malalaman mong di ka nagkamali sa pagpili mo.
Assassin's Creed 2 is a great game - open ended a la Grand Theft Auto minus the autos and in old Italy
- but it's not as great as Uncharted 2.