Most of my rta do not need to be drained. I just take them apart upside down and leave the tank sitting upside down with drip tip removed. Only one that gives me fits is the Merlin as the tank upper/lower ends usually come apart instead of the deck base due to there not being enough/any knurling on the tank base outer ring. Any of the ones mentioned in the first few posts should be good choices. I have most of them in my stash but have not tested all of them mentioned yet.