That's a tough one, actually!
I have and regularly shoot landscape and other stuff with both the 60D and 5D2.
at iso 100 thru 400 they're very similar overall IQ but I actually often prefer the 60D's files over the 5D2's in most cases. I prefer the 5D2 when I want a bit more resolution but it's really quite close
The 60D output is ever so slightly noiser/grainier but it cleans up quite well in LR. It's low ISO noise is very decent and much better than the 5D2's patterned noise.
My 5D2 will often show faint banding noise in blue sky areas, my 60D does not. That's important to me when making big prints.
Their DR is nearly identical from 100 iso up to about 800 where the 5D2 starts to perform a little better.
5D2 is about stop better at higher ISO.
At lower iso the raw files are not really that different in quality, tho you'll have a few more MP to work with from the FF 5D2.
That said, I find I can push my 60D's files considerably more without annoying banding noise showing up in large shadow areas, I cannot push my 5d2 even half as much.
AF performance between the 2 is similar as far as I've experienced (landscapes don't move much)
My 60D has done reasonably well tracking AF for things like running dogs, never tried with the 5D2.
Bokeh on FF is almost a stop better than with a crop camera set to frame the same shot the same way... Not a big deal for most things, even portraits.
60D battery life is really good, 5d2 is a little less so.
As suggested, consider the 5D3 once the price drops to a more reasonable level. It's cleaned up its pattern noise a bit better than the 5d2 and has a number of other useful improvements over the 60D and 5D2.
Just my opinion but if I was a one camera guy right now, and knowing what I do now for the kind of shots I take, I wouldn't trade my 60D for a 5D2. And that's not even considering the articulating screen and more versatile video modes on the 60D if you use them.
LOVE my 60D with a 15-85mm on it. They're never apart.
5D2 is more of a love-hate for me. I keep it cuz I have a 70-200 f/2.8 L mk 2 which is just SO sharp and contrasty for full frame body image goodness. Also like it with the 50mm f/1.4
I'm hoping Canon brings out a low cost FF body with even better IQ (lower pattern noise) than the 5D3.
I have been shooting quite a lot with the 60D for past 1.5 years. I must say I enjoyed shooting with this body even though it is not considered stellar. However, I am tempted to upgrade to the 5D Mark II but holding back for few reasons:
1) Is the IQ between the 60D and 5D huge? Like in the out of camera RAW files. Also I do a bit of PP in Lightroom.
2) I understand the ISO performance in the 5D is better than my 60D, but I tend to not go beyond 800 and try to stick to 100 as much as possible. Will I see substantial difference in ISO performance when shooting in ISO 800/1600. Or even at low ISO such as 100.
3) Any idea if 60D's AF system is better than 5D Mark II or not? I shoot wildlife, but not too often though. Mostly landscape, portraits, street, still life.
4) I have a 24-70 f2/8L, how likely will I get better results when paired with a 5D MkII. Is there any micromanagement function in 5D MkII?
5) They say bokeh quality in full frames are better/creamier, if that's true is it really that noticeable?
6) How about the dynamic range in 5D?
Any other points I may have left out or should be aware of? Thanks in advance.