I mean, colorful is somewhat subjective. I would agree Compressiceps are the most colorful of the commonly seen dwarves, but from the rare pic of Cr. heckeli, I'd go with them as most colorful. They are also the smallest I believe, would love to get a hold of them. They come from the same habitat as compressiceps though, so I imagine they are equally territorial.
I have a theory though I'd love to try if I had a big enough tank. There are stories of compressiceps hunting each other down in a 10ft tank. But what if they are like certain Central American rapids dwellers that become more aggressive in a calm, low flow tank? Keepers have noticed they show far less aggression when kept in tanks that mimic their native, high current habitats. What if comps react the same way? The idea is a tank with massive amounts of shelter but also high current through out. It's almost as if the extra energy these rapid dwellers spend fighting the current needs a release, and in calm tanks this expresses as more aggression. Just a thought.