Not sure if i have ever used vallejo, but my wife has hundreds of diffrent brands that she gets from michaels, none of them worked as well as GW paints for my miniatures.
Most paints designed for miniatures have a hardener added to them to make them more durable. Your regular craft paints might be okay for display pieces, but not for something you're going to handle on a regular basis. Some people swear by the el-cheapo craft paints you can get at the big box stores (after putting a protective clear coat on them).
Different strokes for different folks...