First up, the pros:
I’m just going to get this out of the way: Vallejo is really good. I fully endorse Vallejo’s paint lines and if you decide to use the Vallejo lines, they’ll do you well.
1) Vallejo stuff is fairly easy to get a hold off. The model color lines are aimed at military modelers so they appear pretty frequently in better hobby shops. On top of that, Vallejo’s general esteem in the hobby world means that they can show up in games stores too.
2) Vallejo has a ridiculously huge range. Like retardedly huge – 220 alone in the model color range and another 80+ in the game color range. There’s duplication and all, but shit, 300 colors? GW has 73. Yikes. Plus, I’m only referencing the ranges I use. Vallejo has a ton more. You WILL find a color you like.
3) Great quality. Overall, Vallejo paint has good coverage, good consistency and good drying times (not too fast, not too slow). They paints behave predictably as well due to the overall quality and constancy of the lines.
4) They come in dropper bottles. If you’re not used to it, they can be a little weird and you’ll definitely need some sort of pallet. HOWEVER: the paints store for extremely long times due to a lack of contact with air and mixing is often times much easier as you have much more precise control over the amount of paint you use.
As great as Vallejo is, there are a couple of downsides.
1) The way the paint is made leads to some issues of settling in the bottle. Often times the pigment and the medium will separate. You have to make extra sure the paints are mixed. At one point I was considering an automatic paint shaker. Not too much of a hurdle to jump, but something to keep in mind.
2) In my opinion, the metallics are ass. Just too damn thick for my tastes and as metallic paint needs special considerations for thinning, they just don’t work for me. I also don’t much care for the size of the metallic flakes they use. This is the one case where the GW paint is better.
One of the cool things about Vallejo is the ease of finding color matches to the GW paints. That’s what the game color range is for. Its nothing but color matches to GW stuff. Now, not every color is a perfect match, but most of them are pretty damn close.* Plus, Vallejo has matches for colors that GW no longer makes. So if you need a pot of the old Leprous brown, Vallejo has you covered.
Probably my favorite part of the Vallejo ranges is the inclusion of mixing mediums that come in the same dropper bottle. These are pretty much the same things you can get at an actual art supply store, but without having to buy a gigantic tub of the stuff. I use the glaze medium on a daily basis and always have an extra bottle on hand. As an added bonus, the mediums work for almost all other acrylic paints.
A note on Availability
I’ve mentioned availability as a positive attribute of both the Citadel and Vallejo lines. Maybe it’s not clear why that’s important? Here are two reasons:
1) You don’t have to wait for shipping. You go into the store, and boom, you’ve got a pot of paint. If you need more or a different color, you just go back.
2) Its so much easier to judge color values in person. This is especially true for a range or color you’ve never seen before. Most places supply a color chart online, but they’re just not good at giving you an accurate representation of a color.
It’s a real bummer to order what appears to be a delightful dark red only to find that you waited for 5 days for something considerably more pink than you would like.
PERSONAL EXPERIENCE NOTE: Foundry’s Madder Red set is decidedly on the pinkish side of red. Though this may be due to a mislabel.
--------------------------------------------* I ran into a strange situation with the difference between VGC Charred Brown and GW Scorched Brown. Scorched Brown has a distinct red tint to it. Charred Brown… does not. Its more of a muddy brown. They dry to about the same color, but they will mix very, very differently with other colors due to their own particular balance.