7 string reccomendations
Back to the original question...
The UV/K-7 and the ESP Stephen Carpenter model are kinda different beasts.
The ESP has a neck-through body and probably a painted neck, which some players may not like too much. It's also got a more unconventional pickup layout (which personally i like) and no trem... again, not for everyone.
I think pretty much everyone knows what to expect of a UV. They're great guitars. From the sounds of it, the K-7 will be excellent, too, with slightly more subdued aesthetics.
I quite like the looks of the ESP H-207, though its lack of trem would bug me. I don't use the trem on my guitars all that much, but i do like it to add subtle shading to chords or to do subtle note slides and dips. I'm surprised ESP doesn't offer a 7-string in their standard line, just in the Korean-built LTD series.
You could also consider getting a Carvin, too... their DC-727 and 747 look like great guitars for the money. I do wish they'd use some lighter woods for the body wings, though. Solid maple guitars are heavy!
But if you're interested, give the self-build route a go! Warmoth has everything you'd need to make a 7-string, though their body styles are limited to two choices. Still, it opens up a lot of possibilities for getting exactly what you want.