The OP's stated criteria narrows the field considerably. "Adjust the voltage" points to variable voltage, selectable voltage (i.e., the FistPack), or regulated power (i.e., the Darwin).
"Pretty" of course is in the eye of the beholder. I do think that the
Infinity and the
Ali'i (VV version) win. Although one could make a case for the
Darwin (which
I would call "stylish"). [Yes, I know that there is a lot more to the Darwin than style; I'm just working off the "pretty" criterion at the moment.]
Now that the
Saber Touch (VV) doesn't have to look like a Grecian column, I think it also is "pretty"...
...but I wouldn't call it "easy to use."
The
prices of these three devices (Saber Touch is disqualified) are dramatically different: $80 for the Infinity; $185 for the Ali'i (VV), and $230 for the Darwin. If price is no object and you like the appearance of all three, get the Ali'i if you want a juice feeder and the Darwin if you want the Rolex of PVs.
As for me (on an extremely tight budget), I'm getting the Infinity and continue to drip.
EDIT: Oops! I just noticed the OP's "nice price" criterion. So, follow my lead.