Tips

Uncharted         metascore   88

Uncharted 2      metascore   96

Mass Effect        metascore   91(360) 89(PC)

Mass Effect 2     metascore   96(360) 94(PC)

Mass Effect 2, definitely.

Don't get me wrong, both were great games but while Uncharted 2 was just Uncharted on a bigger scale, Mass Effect 2 actually felt more like a sequel.

Mass Effect 2's improvements were just so much more significant to me with fixing all the glaring technical issues and the streamlining of all the systems just made it so much better. Uncharted 2 felt more like polish rather than such a drastic fix (which could say more for Uncharted).

i think one of big improvements of Uncharted 2 is the famous multiplayer

IMO, there's way too much emphasis on Metacritic. If you're gonna use metacritic then the answer is Uncharted simply by the gap alone.

I think you just mention AC. Thats a sequel that has improved A LOT.
Uncharted 1 to 2 isn't, or at lesat it doesn't seem like a big step if you play in that order and don't go back.

Uncharted 2. It took everything from Uncharted 1 and made it bigger, better, and smoother, then added a huge online mode and co-op.

Mass Effect 2 stripped out half of Mass Effect 1 and made the remaining half bigger, better, and smoother.

Love both games dearly, but Uncharted 2 is clearly ahead in this particular race. For me, at least.

Dunnow about ME1 or ME2

But Uncharted 1 was a ok game. nothing more

Uncharted 2 was a legendary game

so I'll vote for Uncharted 2

Uncharted 2, definately. Both brilliant games and franchises but...

ME1 was already a very good game which was let down on the technical side (long loading/elevators and relatively poor gunplay) whereas Uncharted was good but otherwise fairly average compared to other games on the market.

U2 added multiplayer, co-op, better graphics, a proper stealth mechanic, better pacing and generally more polish all round.

ME2 improved the gunplay and refined the experience but as far as I was concerned the base experience remained the same.

Uncharted 2.

They were both quite similar to the first, just with pretty much every single problem removed, and what was left was improved. Uncharted 2 just added in multiplayer on the top and that is what gives it the edge (and ME 2's cover system still annoys me)

Mass Effect 1 was shit compared to Mass Effect 2.