The protank is 510 thread and doesn't have a skirt, the evod is ego thread only. The mini protank is ego-only still. The anyvape davide is the same way as the protank, 510 on large ego on small. Protank comes with a ring to put on the ego threads if you have a raised platform.
But evod/protank/davide/viva all use the same replacement heads, so if you have the budget, you can mix and match to see what you like and since they all come with extra heads you won't be out much if you decide not to use one. I took one of the evod-type heads apart last night and they are actually rebuildable as well, they aren't glued anywhere, at least mine weren't.
Oh and to throw another option into the mix there's the new Kanger unitank. It uses the same heads as well.
BTW Katya you do get used to the looser flow if you stick with them. It does seem weird at first though. Not much you can do about the noise... my coworker says they sound like when someone calls the PA system by mistake and leaves the phone off the hook (low static).