My present all-day vape is Vermillion River's Kentucky blend #7. The premium is also excellent. It has an RY3-RY4ish feel (tobacco, slightly sweet), but a really nice mouthfeel and a good throat hit, plus the flavor is wonderful. I highly recommend VR's stuff. Also, I found that while it's not an all-day for me, Liberty Flights's RY3 is also a good juice. I've heard good things about Backwoods Brew, too, although I haven't yet experimented there.
I'll also say to skip the prefilled carts (they're not necessary), but I will also highly advise looking into a Riva tankomizer - the Riva-T is a great clearomizer that holds about 2ml of juice. It does require a syringe to fill, but now that I'm using these, I'm absolutely hooked on them. I get them from Cropduster 901 (who is apparently a former ECF-denizen who sells a few things on the side), as his prices are the best I've found for that one item -- link is here:
RIVA-T TANK - $4.99 : Cropduster901!, Home of the B-52