This seems to be the great debate amongst war gamers. Granted there are several other brands on the market that some would argue are superior... Reaper, Formula P3, and Coat d'Arms to name a few. However we are here to discuss what seem to be the two most widely used brands amongst Warhammer hobbyists.
Citadel vs. Vallejo
I have personally used both brands of paints. Having started out painting my models with acrylic "craft paints," getting my hands on a set of either brand was a godsend for me.
I would compare the coverage of Vallejo paints to that of the Citadel foundation paints. Sans a couple of the lighter, brighter colors. Vallejo Game Colors apply smoothly and evenly with little effort and thin flawlessly, especially with the aid of their own brand thinner.
Citadel paints have been a hit or miss experience for me. I find coverage to be so, so unless painting over a white base coat model. The foundation line is great however. With a bit of thinning these are great for general use. I'd love to see this formula worked into the regular line of paints rather than paying extra for the foundations set.
Vallejo steals the spotlight here as well. The dropper bottle makes it very easy to mix exact paint recipes on your pallet or in another container. So long as you're prompt about putting the caps back on, these paints will not dry out. At worst you may find your self using a pin to unclog the dropper tip from time to time.
Ahhhhh the dreaded Citadel pot! I don't mean to be so hard on Games Workshop... but the Citadel pots just don't cut it. The problem lies in the cap. These things just do not seal well enough. If you go any length of time between painting (which I do often) you're bound to come back to dried up paint. The design of the pots while not all that different than many others out there is also not very conducive to mixing. Once spoiled by the dropper tip you really start to wonder why anyone would put themselves through such an ordeal!
Citadel has a wonderful line of wash's you can spend a pretty penny on. These are super helpful for taking basic paint jobs to the next level. I suggest everyone experiment with wash's at one time or another. But there's an easier way!
Vallejo offers a line of wash's as well. Where Vallejo shines however is with this wonderful stuff called Glaze Medium. Mix a bit of this in with any of your Vallejo Game Colors and you have a full range of wash's! It has worked exceptionally well with all colors I have tried to date.
I'm afraid Vallejo wins out here as well.
Vallejo 17ml bottle - $2.20
Citadel 12ml pot - $3.70
I suppose I'm a bit biased but Vallejo is just a better value for the quality and quantity of paint you're getting. I'm glad I made the switch to it. I'm never looking back!
As a courtesy to all the wayward souls who are still using Citadel paints I have provided a Citadel to Vallejo paint conversion chart HERE.