Im primarily looking to buy one of these two games to play in 3D. So first of all which has the better quality 3D and ofcourse which is the best game of the two. Graphics wise and gameplay/performance. 

Ive looked a bit on google and their isnt anything about a comparison between the 2 in 3D, and mostly just fanboy comment saying GT5 is better.

I don't like both.
For me best Gran Turismo is 4 and 3.
But i said Gran Turismo 6>Gran Turismo 5

Did you play them in 3d either of them

Improved physics on GT 6 and slightly prettier.

GT6 has better physics and looks slightly better. Also, GT5's online was shut down about a month or so ago, so you can't even get the DLC cars and tracks (GT5 XL might have most of them). I never played GT5 in 3D, but I did play GT6 in 3D. It's cool, but you wouldn't want to actually race like that.

Well, I have both and played them on 3D. The 3D effect on GT is pretty subtle but I prefer the GT6 3D effect since the config options seems to allow going for a stronger effect than the maximum that GT5 allowed. I had the impression too that GT6 had a little less crosstalk, but both are actually good in this aspect. They are actually pretty similar on 3D, but GT6 has slightly better visuals.

Standard cars look way better on GT6 too. In GT5 they looked horrible, but in GT6 they are pretty similar visually to the simpler premium models and most of the time you can't notice them unless you zoom in with photo mode on replays. Since you are looking for the best visual experience, that is surely a deal breaker for GT5.

Since both are similar in 3D, I would recommend getting GT6 since GT5 is without online now and GT6 still receives a lot of new things with updates while GT5 is done with that now.

Of course, if you want the best 3D on PS, Killzone 3 still is king, UC3 comes second and I enjoyed Resistance 3, Epic Mickey 2, Sports Champions 2, Shadow of The Colossus and Puppeteer too. Arkham City was decent and MK was pure crap on 3D.

Worst thing is that the resolution in GT is reduced for 3D. Killzone suffered some visual downgrades for 3D, but resolution stayed the same and the amazing 3D effect they added made it completely worth. I finished KZ3 and UC3 on 3D more than one time, while I just played 1 or 2 hours in 3D on both GT games.

I played 5 in 3d and it is not impressive, the best 3d so far is Killzone 3 and Uncharted 3. These ones are pretty neat in 3d.

Yeah, it was a little taxing on my eyes after a while of hot lapping in GT6. I need to play KZ3 and UC3 in 3D. So far, I've only played GT6 and Puppeteer, and the latter is amazing in 3D.

Awesome thanks people GT 6 is it.

On a side note does anyone have a spare Zavvi.com code they arent going to use