The answer is pretty straight forward, the PT 2 and its not even close.
The puritank is only able to be partially disassembled and is a glued
tank, the PT 2 can be completely disassembled and uses no glue to hold the
tank together.
A more realistic comparison would be the Protank 1 vs the Puritank. In that comparison, id say the Puritank holds a tiny advantage in that it holds just a bit more liquid and has removable drip-tip. That said, my PT 1's, PT 1.5, and PT 2's all get used more than my Puritank.