I meant, what are you looking for in/from a delivery device.
When you say "it", which of the dozens of its are you inquiring about.
Everything in vaping is a matter of personal preferences, what I or many others think is the best 'tank'/delivery device, you or many others might think is horrible.
What features are important to you.
Like I said, any delivery device that has a 510 connection with replacement heads that use kanthal or you use kanthal in an rba of some sort in watt mode will work on the m80.
Just me, my favorite is a P3 threaded Kabuki (won't work on 510 threaded power device), I have several of the 510 kabuki's I don't care for at all, they sit in a box unused.
Triton v2, nautilus x, triton mini, nautilus, toptank mini, 1st gen crown, herakles I don't recall which version I have 3 or 4.
I was a fan of the atlantis for quite a while, I received 4 boxes of replacement heads with the wicking material packed too tight I have no desire or time to fiddle & futz around with vaping stuff so all the atlantis & 99% of anything that requires building/rba/rta etc now resides in the unused box...
I could go on for a page with what I've tried & liked.
What is most desirable in a delivery device to me may be completely different from what you are looking for.