as Jimmy says, I make heavy use of army painter sprays, their washes are also top notch, I used the red wash on my speed freaks, and the strong tone quickshade is a dead ringer for devlan mud
I'll also recommend P3, if you like the whole pot-painting feel, then they're great, they also come full to the brim rather than a small dribble, you probably get 2-2.5 times the paint in a pot that GW sells, they're also liquid pigment so don't dry out as much and work really well in an airbrush, they also have a long drying time so if you're into layering and wet-blending they work really well, they are loaded with pigment but also thinner than GW paints so are best built up in layers
the only things I can find fault with P3 about are their somewhat limited range of colours (they encourage you to mix up your own shades which is fine but not always consistent) and limited availability.....