GT5 will be the only full game of the series on the PS3. That's a pretty big advantage, I think.
Then again, I wouldn't be surprised if Halo Reach outsells Halo 3 (though I don't think it will).
Well, if I had to bet, I'd say GT5 will win. However, I can't say I'm confident in that choice, it can really go either way: GT5 declining due to competitors, Halo declining due to the sequel effect, GT5 over 10 million because people have been waiting forever, or Halo Reach above Halo 3 due to larger userbase (MW2 buyers)...
It'll be interesting to watch, for sure. If Halo Reach doesn't come out opening stronger this year, though, I don't see it catching up. GT5 is stronger in the EU region, and is also a racer, both of which tend to sell more over time (as opposed to a shooter with sales mostly from the US, a frontloaded region).
