I have played racing sims my entire life, I own both systems, I've played nearly every racing sim available for ps1, ps2, ps3, xbox, and xbox 360 (including jp only releases of GT)  I love racing sims.

If i had to apply total subjective scores to the games like every other random video game review site does I would go:

GT4 (ps2) - 9.5  for the system this was amazing.  There are it's limitations i.e. damage but aside from that the realism is beyond insane for a racing sim, let alone on a console

Forza  - 9.0  Great game, looks great and is a great first step for microsoft to take on the legendary namesake of rsims that is GT.  Considering it is on a next gen system compared to gt4 on last gen system, it is somewhat lacking

Forza 2 - 9.5 Great lineup of tracks, cars, damage, continued improvements. 

GT5:P - 9.0 - well, for being only a portion of the actual game to come this game is phenominal.  With damage to come for GT5 full edition it may be the only true 10 or close to 10 most will ever experience in gaming (if you like rsims).  Only reason this is lower scored than forza 2 is becasue of content limitations

GT5: no rank - NOT RELEASED

Forza 3 : no rank - NOT RELEASED

So my final analysis:

For absolute realism: GT would be my preference. 

For fun: toss up, I would prolly play a round or 2 of both.

Thoughts:  GT is an established, iconic name in the world of racing sims and a hit seller for the playstation brand.  Forza is the new kid on the block.  For any developer to put forth a game that can even compete with the established name of Gran Turismo is amazing.  Full version to full version GT will probably win the battle of future releases but they have much more experience with the styling.  The realism of GT is astounding though.

- my unbiased review, i am a fan of both.  It comes down to realism for me both have enough content to please the masses.

Also... first post.  I'm a noob :(

If you continue to compose high-quality posts similar to your first one, you will have an enjoyable time on the forums.

I find it funny that people talk about realism in GT when you crash at over 100mph and nothing happens to your car lol, that aside, I played GT 2-4 and now Forza 2 and its much better than GT, the physics is better, the cars feel like real cars and all handle different than others and the damage system makes it just so much better than GT. The customization you can do to your car in Forza is pretty incredible.
GT is still an awsome game but its just more of the same all the time, feels like the only thing changing since GT2 is the graphics, all the rest is the same.

GT is the best racing game period. PS3 fanboys brag about it and X360 fanboys know it deep inside. Forza does not even come close(for those who said that), as I've played both.

I believe GT is the one series that really defines the racing genre and set new level for it. More so than any other games. Moreover, there is a reason GT is considered by Forbes to be the most valuable fanchise in the videogame industry, Even ahead of Final Fantasy or GTA.

Forbes seems to have a selective memory that doesn't include multiple Nintendo franchises, Warcraft and the Sims.

I remember seeing the forza bundle in all the stores until late March, so that puts it at about 4+months at retail.

WTF I AM DOING HERE??? THIS IS A FAN BOY NOWHERE DISCUSSION.

HOW ONE IS BETTER THAN OTHER IF THESE ARE FOR DIFERENT CONSOLES, MY GOOOD.

CLOSE THIS THREAD...

I have no idea why this is even a question. It's like lets argue football, who is better, the Titans at 8 and 0 or the lions at 0 and 8, go!

The Gran Turismo games always have been the gold standard of racing games with insane amounts of cars, tracks, the best graphics and....everything else. There is simply no comparison, the various xbox racing games are also rans every time.

There is not a single feature in any Xbox racing game that is an improvement on the GT series, not one.

GT looks better but I prefer playing forza.

Ummm...online? Damage? I'm not trying to say one is better than the other, but Forza and other racing sims had numerous features that GT has to catch up on. For you to say there is nothing they do better is very ignorant.

The Lions/Titans comparison is cute, but is so rediculously off considering that both series are a success in sales numbers, both similarly critically acclaimed and are both liked very much by their fans.