Well, most FC'ers may recall what a hopeless Alan fanboy I am at this point, so I feel as though I cannot be impartial in any way.
Jesus titty-fucking Christ I'm willing to wait well over a year for this guy's work! Fucking ridiculous. I wouldn't wait over a year for anything else in the fucking world. I've owned it for a year now and I still am dumbstruck by its beauty and design. It rules me like no other.
But I have owned all three, so I suppose ...
But honestly, I really don't know what I'd choose in this position. Both the UD and Nano have so many positives each that, as MANY others have said, you can't go wrong either way.
My general advice from the past still seems to ring true: don't put too much thought into it, because you'll end up with more than one kind of log vape anyway, eventually. It's a rare breed who can own only one.
They'll both probably have 4/20 sales, so it'd probably pay off to wait a few days.
Sorry for the lame response, but ... seriously.
For fuck's sake, look at all the love shown here for all 3 current logs - why on Earth would you only own one brand of them if you could afford more?
More wood = better life.
That
@SSVUN~YAH dude and
@NickDlow fella have it right - get 'em all while the getting's good! The time is now!
Just fucking pick one and go with it! And plan on buying the other before too long and the HI when your turn comes up.
Short answer: Heat Island with a Voltage Keeper. Fuckin love those VK's.