http://www.tomshardware.com/reviews/phe ... 60-13.html
A good read.
I think the Phenom II's are good if you don't want the extremes, for example a Phenom II 955 Black Edition and a 4870 1GB is a computer I wouldn't say no to

But the article does show that the i7 does have noticable performance advantages over the Phenom II's when on a comparably priced computer. If they went lower in price budget though, they wouldn't have the money for decent GPU's to go with the i7, so I guess the Phenom II would win after the budget was lowered to a point.
Well to put it this way if I would buy an i7 system I would have something like this:
i7 920 CPU -> around 230 Euros
Mobo -> Around 200 Euros
DDR3 memory -> 100 - 150 Euros.
Which brings this total to 530 - 580 euro's.
AMD cpu -> 170 Euros
Mobo -> 130 Euros
DDR3 -> 100 - 150.
This would save me more then 100 euro's on these components, this combined with the fact that I do not like to spend more then 800 Euros on a PC, i7 simply is not for me, then I would need to increase my budget to around 1000 euro's.
And the actual performance advantage I would get out of these 200 euros simply isn't worth it for me.
So this basicly also wraps up my answer to the original question -> the best CPU for TF2 depends on the budget you have for your PC.
..... Long life the hardware wars.....