Innokin Zenith. I think it is 23 mm. I pbon't own one as I'm not into mtl other than occasionally pod devices. This is the tank designed by pbusardo. Plenty of reviews to be found.
If you want a refillable pod, the Aspire Breeze is supposed to be good.
You can use og Nautilus coils in the Triton Mini if you can find one. Looks like a regular tank, which I much prefer.
There are some AIO setups too, like Joyetech D19, eco AIO, and Innokin T20s.
You might like nic salts with any of these, but strength would vary.
Vapecrawler is a good site for price comparison.