The ultramel is pretty sexy, but being more of a color mutation, and a recessive gene, it might not be too sought after. However, the color is really cool. Axanthics are strict color morphs, and they're not really expensive. The multiple lines probably helped get them produced faster. I think ultramel is also slowly heading in that direction. There's criders, ultramels, and monarchs. There might be a few others as well that we haven't seen yet. I saw outback reptiles selling a w/c one that wasn't proven. I like them, so I'll eventually get into them, but I don't think they're going to hold their price tags for very long. Not when they must compete with the multiple lines, and other, more powerful recessives.
Leopards are another good one! Pretty powerful pattern mutation, but they apparently have a super form. I believe it was Greg Graziani (correct me if I'm wrong) who showed a picture of a super leopard. I'd have to find that link lol. They'll probably end up being a staple pattern morph like the spiders and pinstripes. I like 'em a lot!