Billow is better. I've got the v1 and the fogger v6... The deck is about the same size on both, but the billow's posts are sturdier, for one thing, and it is actually more forgiving when it comes to wicking. Don't get me wrong, they both have a learning curve, but the Billow can be done a bit easier with less attention to detail once you get the hang of it. Both have nearly the same size
juice channels, can chain max vg easily. Some complain of leaking with the Billow, but once wickrd wicked correctly, mine can lay on its side all night with no puddles...it does seep from the bottom screws, but so slightly you wont notice until you remove the tank and need to swipe the top of your mod with a finger. Lol re filling, I never use the bottom fill, I take the top off with my fingers over the airflow holes, fill and then blow out any excess. Less comes out than the fogger (maybe half as much) and the total
juice capacity is double. Flavor is about the same, good on both, airflow is more adjustable on the B also, full open is a bit wider than the F (still not Lemo ish air, but I've yet to find a wide open flavor tank) -- 510 is still adjustable - can't think of much else to say, lol. I swore by the fogger til I tried the Billow. Both are good but the fogger sits on the shelf now lol