I appreciate all the advice. At this point, I'm mostly looking at the Aegis 100w, and their newer Aegis Legend 200w. Leaning towards the 200w Legend.
One thing I notice is that when I think of 18650 batteries, I think button tops. Those worked with my provari, so I have numerous "extra" batteries that still work, they just don't hold a charge like a new battery. And I have several high end flashlights that use them. (If you want a good flashlight, and haven't seen an 18650 powered LED flashlight, you'll be amazed.)
But I'm guessing that button tops won't work with these and I'll need to move to flat tops. I can do that, it's just not what I'd consider ideal.
The "legend" version is dual 18650's. That may be great, but way-back-when, there were a lot of problems with mods that used stacked batteries. It simply made things less safe. Should that be a concern with the Aegis Legend? If it's not, then the dual batteries means needing to swap out less often, and I sure like that part.
I don't know why I would need 100w, much less 200w, but I plan to use this thing for a long time, and wouldn't want to buy it, then find some reason later that I wanted the higher wattage limits.
I may stick with the Aspire Nautilus tanks I've been using, but while I'm upgrading, I'd consider options on that too. I know I want something simple that just works. I don't want to tinker with it, and I'm not going to roll my own coils or anything similar to that. Easy to refill, consistent vape, tuff enough to handle most drops, those are all high priority with me.
Several people have mentioned MTL, but I don't know what that means.