I personally think Grand Turismo 5 because the series is more popular than the Forza series. I think the lifetime sales of GT5 will be twice as larger as Forza 3 lifetime sales.

What do you think?

I thik Gran Turismo will sell more given its history. Btw, no D in the title.

Both will be good games, but my side lays with GT5.

Forza, because Grand Turismo doesn't exist.

forza, because when the previous gran turismos were on a system with a much higher install base

Since Forza doesn't even have a quarter of the quality Gran Turismo has...

GT5

 ^ U said it

But of course GT5 will bcus its just more popular around europe and japan. America can be about the same if there are a lot of racing fans in america who plan to buy fz3, but GT5 will kill it in sales WW.

GT5 no doubt, I think indeed that in the US FM3 might be on par with GT5 but outside it GT5 will beat FM3 sales to dust.. BTW GT3 sold 9mil units and launched at a userbase of 14mil PS2s...

apart from there being no "grand" turismo,- as bad genome said, I'd guess forza would sell more simply because there are 8 million more potential consoles to sell to.

GT5 should handily outsell Forza 3 in its first week and lifetime. But the very fact that people are comparing them so much really shows how good Forza has become. Even though GT is still the market leader at least there's some serious competition now. Competition means all the developers involved will pull their collective fingers out of their asses and make better games.

Gamers win.