I would say the Siren V2 is pretty similar, I wasn't a fan of the Nauti 2 as I found it a bit too airy for me & found it frustrating with leaks & hard to fill but the Siren is a good RTA that is easy to build on and similar Vape to the nauti 2 in my opinion.
I'll agree with Ally and say the Siren 2 which I believe is a very good atomiser. Now I've managed to tame the True I can say that the vape it delivers isn't bad and you can certainly dial it down to a nautilus like draw. Problem is mine leaked terribly straight out of the box which transpired to be down to an o ring. The one fitted AND the spare were both faulty so I'm reluctant to recommend it in case you suffer the same fate. One I've seen mentioned (but don't own) is the Salt RTA which actually even resembles the nautilus. That ones only 18mm though so could be troublesome to build perhaps.
I've got several that I frequently use and quite often go back to the doggystyle clone which for about $15 is a very good buy. Bottom fill and a plastic threaded tank but I've yet to break one and spare tanks are available for pennies. I'll have a bit of a better think over the weekend and perhaps put some more thoughts down.
Just thought of another being the Darwl V2 clone which comes supplied with air inserts and tank options to suit most I would imagine. I use mine frequently and find it very satisfying. No adjustable airflow though just the air inserts. Apologies if I mentioned clones too much!
The Berserker mini is good but I found myself bottom filling it due to leaking issues which doesn't bother me but it's a thing. Again airflow can be dialed right down.
I've never actually compared anything to the Nautilus side by side and will say I'm going from memory.
if so, a lot of MTL apers are finding their happy place with that
apparently a great bit of kit
I bought the DL clone of this from 3fvape not long before i hung up me spurs, think it went to live with Ally from memory, havent ever gotten a review out of her for it, so assume its in the "last resort" drawer or she passed it on.
Careful ordering from 2fdeal if you're an Aussie, orders come via Fastway who delay packages or in my experience,refuse to deliver them & expect you to run around after them,lying about the tracking the whole time.Fastway has lied about & failed to deliver 100% of their deliveries to me.Only choices to avoid Fastway are untracked & expensive DHL
The geekvape ammit mtl rta isn't a bad bit of kit.. can close down the airflow to be like the nautilus 2. Or alternatively there's the gate rta by ambition mods. I've not bought one yet, but it seems to be a cross between a kayfun and a skyline rta..