Don't get me wrong here, I love all my smok gear, both my aliens, me gx350 and the skyhook.
But you mentioned "build quality", Smok are not always known for their quality. If you go for an alien and you get a good one, it's gonna be almost bullet proof, just like my gold one. But if it's one of the not so well made one's (so to speak) it could well fall apart in a week.
I've been lucky and not had a dodgy one yet.
Having said that I have had other brands in the past that have failed in less than a month.