I have tried several metallics, because I was never really satisfied with the size of the flakes....
I don\'t like the Vallejo game colour metallics, the binder, flakes and the pigment seperate too fast for me. I put them on my pallette, thin it down, apply one thin coat, stir like crazy, apply another one.... too much hassle. Haven\'t tried Model colour metallics, my LGS only carries game colour.
Vallejo metallics on an alcoholic base are great. They give a very smooth coat without any thinning and the flakes are not only very finely ground but the paint also looks gorgeous when it reflects light. Just like real metal. Problem here is that they dry far too fast and require shaking like stupid before they can be used. Often I put some on my pallette, get it one the brush, at once apply about half of it because the other half is already dry, repeat it two times and then clean my brush because the bristles are effectively glued together with dry paint. Apart from that they are great, but that\'s a pretty big \"that\". Also, they can not be cleaned up with water - I use aceton with good results.
GW metallics are better I think, I have a pot of chainmail that really works well: It can be thinned down very well while still covering. The problem here is the pot (screw-top, no eyedropper. Yuck.) which really let\'s the paint dry up quickly, no matter how much I take care of it. I always add a drop of water after I opened the pot. Still, I have the feeling the flakes are too big and don\'t go on smoothly.
Last on my list is model master metalizer paint. It\'s supposed to be applied with an airbrush, but works well with a brush too. It is incredibly thin and still covers well in two or three coats maximum. You have to shake it like crazy again, the binding agent and the metal flakes seperate in less than ten minutes
I am not sure what the base is - can clean the brushes with water if I am quick enough after applying it, but when it starts to dry (without being completely dry yet), I need aceton. The paint has a great shine and the flakes seem to be very small. The pot says you are supposed to buff the metalizer - I usually don\'t do this, but it actually works.
That\'s all I have used so far. I would say like the metalizer paint best - just follow the order in which I listed the paint, basically that\'s my opinion of worst to best