Mountain Oak Vapor is pretty good straight out of the mail (it arrives pre-steeped, iirc). That said, I haven't yet found a
juice that didn't get at least a little better given some time to sit - Halo and Mountain Oak included.
(Edited to contradict myself): Actually, that's not true. Dekang and Hangsen seem to taste the same no matter how fresh it is or isn't (I've had some that was less than a month old and some that was 5-6 months old, no difference that I could tell). But one could argue that Chinese juices pretty much steep in transit and on the shelves. I've never had a made-to-order or "gourmet"
juice that didn't get at least a little better with steeping, I'll put it that way.
Some made to order companies also sell "pre-steeped" juice, if that's what you're looking for, but you will pay a premium for the pre-steeped stuff.