Good point. The Nautilus (the big one) mostly comes with BDC coils and they are less reliable. Some people say they are useless, but I got 12 hours happy vaping from one, once.
Exactly this. Switching to the BVC heads improves the Nautilus from zero to hero.
If you're looking for the latest and greatest, Aspire have the Atlantis and Kanger have the sub tank out right now. Both are sub ohm clearos (with the Kanger having an extra piece that changes it to an RTA) designed to be run at 20-35 watts.
There are a lot of reviews out there on youtube for both of them. From everything I have read and seen, they have both been very well received. If you do decide to go this route, just remember that you'll need a mod or a mech that is capable of firing a 0.5ohm coil and putting out around 30 watts.
Review below is for the subtank, but he compares it side-by-side with the Atlantis. He also has a separate review on his channel for the Atlantis.