Someone ... will say something made by smok.
Not sayin' best, but my Alien and AL85 both still work. And a fairly intact finish despite pocket carry and whatnot.
I'm also fortunate that my lost vape efusion Duo has to be at least 3 years and the Lipo it came with is still the original. Never had to replace it or swap on the battery sled. But I don't use and need to charge it daily. The shiny aluminum frame around the USB does have some scratches from some poorly aimed stabs at the port.
The best mod is the one that works for you, is safe to use in your typical environment, and feels good to use. Other than board performance for something special like temp control it's all subjective. Besides, build quality is only one factor. Would you use a nice handmade stab wood mod in a setting where drops and jostling is likely?