I have a few Vallejo colors. I mainly use Tamiya and mess around some with Model Masters.
Vallejo is, in my opinion, just about the best paint out there as far as how even it goes on, how complete the coat is, how durable the paint is (you don't have to immediately seal it), and how rich the color is.
Very easy to brush on with a paint brush. No brush strokes and it comes perfectly thinned. Also doesn't gunk up the bottle I have notices.
I have also sprayed it on. It is very thick and I used something like 30 PSI and shot it right out of the bottle (since it was already thinned) with no thinner or retarder. I didn't have much, if any, trouble cleaning it up.
I can say the metal colors are too thick to paint. Clogged up the brush but good but cleaned alright. Just too thick to get them flowing.
For future Luftwaffe builds I am thinking of using Vallejo colors exclusively. I wasn't there so of course I can't say, but I always thought their RLM colors were what it should look like. Just wished they had a bigger selection