This, plus the stuff that is available has not been around for more than a few years, so how could we know what will last the longest?
My best guess is, the simplest devices from the most reputable manufacturers. My MO is variety. A couple of this, a couple of that. If I had to pare it down to only a few mods I wold say the less electronics the better. Mechs. Unless you can get replacement boards and have the skill set to repair them, I figure boards could be one of the first thing to quit. Internal batteries are another weak link.
I do have mostly regulated mods and tanks with drop in coils because there are going to be times when I can’t build. And a lot of the ones I have are a couple years old with no signs of failing yet, so I’m pretty sure I have enough to last me.
The Lunas were a good investment, I think, they seem to be holding up really well. If I can get 2 years out of each one that’ll see me to 76. Some I got for $30, some I paid more, but all told under $400 for 10 of them, or as long as we’re doing comparison math, about 5 weeks of smoking.