so.which one?

Which one has dynamic weather?

Well, oddly enough, the two are actually comparable... I think it's obvious that Forza 5 looks better, but not by much in the comparisons that have already been posted. It is important to note that Forza is already having to make full usage of the Cloud, so I would go so far to say that they are equal, graphically, but GT6 still has the better racing physics (if it's like GT5).

Is it the one that uses PS2 assets?

No competition dude ...

DriveClub would be the obvious choice here.

On a more serious note.

I think Forza is currently winning on car models. The Club is winning on "tracks", I guess you could say. DriveClub seems to be winning on everything else.

the crew and driveclub added.

This is ridiculous, there's no way or shape to compare both games in the graphical department. The sheer amount of assets that Forza 5 can render thanks to it being a much higher end hardware can't be matched by the assets that GT6 can render. It's only natural, we're talking about two different generations of hardware here.

These kind of comparisons are really getting out of hand now, and it's only a breeding ground for a useless and pointlessly long amount of banter from both sides that will only fuel the senseless "console wars".

If we're talking about exclusively about games on the same hardware, from what I've seen then I'd give the edge over to Forza 5, mostly due to the lightning engine, which I found to be just lovely.

GT6 in terms of realism... better lighting and dynamic effects.

Pure graphics... Forza 5... looks cartoonist but it have better graphics.

Overall? There is no comparision here... Forza 5 needs to cost $5 to be a better overall value than GT6.