Since my last post I've been working more with the paints I have bought and changed my mind on a few things.
While I do love the stickiness of the Vallejo paints they are not well suited for blending. They lay down an excellent base coat (and I have read they are likewise great for layering - I don't have enough colors to try it). They look a bit "out of the tube" though, very bright and flat. The Reaper paints in contrast mix and blend beautifully. I mixed the red I have with the flesh tone and wound up with a wonderful leathery pink that I used to paint a grimoire (Malifaux Student of Battle if you care).
I have also continued to research (I am planning to buy a paint set) and apparently the Vallejo paints have a very bad separation problem. I haven't seen it yet but I don't do tons of painting so paint needs to last for me. The more I use the Reaper paints the more I like them, so I think I will probably buy a set of Reaper paint and only possibly buy Vallejo for colors that are tricky to basecoat - like yellow for example. Also, Reaper I can buy directly from them instead of going through unknown ebay dealers which to me is a plus. I have had great experiences with Reaper's customer service and they ship like lightning.
Lastly, the more I work with either of these paints the less I like my Citadel paints. Some people swear by them, and some people claim there is no difference but if I could go back I would never have bought them. They are more expensive and I find them much more difficult to work with than either of Reaper of Vallejo. My recommendation for a new painter would be: skip Citadel completely, buy a few of Vallejo and a few from Reaper and try them out, see what works for you. I have heard mixed things about P3, but I've never tried them.
Edit: One good thing for a beginner about Citadel paints for beginners is that they have pretty good coverage. I think it is hard to get a precise edge with them though due to the consistency of the paint. So a beginner might be able to lay down only a coat or two (which is satisfying) you will have a hard time not obscuring details and getting paint all over the model. I think a beginner might be more satisfied with Vallejo if coverage is an issue. Reaper is thin, which is nice for details.
These are both good paints with strengths and weaknesses. If I were rich I'd buy both. In reality I think I am going to buy heavily into Reaper and supplement here and there with Vallejo.