The only tank I'm looking at now is the Billow 2. Have two Billow 1's and love 'em, except the tendency to weep. This version is supposed to eliminate any "hole" in the bottom and maintain the juice capacity. As far as subtanks go, I only own 2 Kangers. Has the rba deck, very simple to rebuild the stock coils. As far as the other subs out there, if it doesn't have an rba deck, then no thanks.