they all have their advantages and disadvantages.
gw, vallejo model colour and most of the game colour range are cracking paints.
(never tried reapers stuff)
the only reason i tend not to use gw in general any more is due to the price, although their foundation paints are fantastic for glazes.
any one who doesn\'t like the gw metal prices but loves the fine pigment gring will love vallejo model air metals, just as fine and cheaper
saying this, if i was a person who mainly picked stuff up from stores i actualy visit instead of online then i would more than likely still be using gw\'s range as it\'s pretty good when i\'m honest about it.
tamiyas paint\'s are great for airbrushing, never had much luck when trying to brush paint with them though (apart from tamiya\'s clear red)
i still use gw\'s inks for glazes as well as adding to colours occasionaly for added oomph.
going to have to go to coaties for my ink goodness when they are gone though.
p3 paints are pretty damn snazzy, but my vallejo do just as good a job, whilst retaining a matt finish (their colored metals are pretty cool)
coat d\' arms are nice paints, cheap as chips but unfortunately have a satin finish so need the dullcote love showing.
foundries paints have more pigment than coaties but unfortunately have a price tag like gw\'s (and a stupid price for a single pot)
hope that helps someone.