Using mods with built in batteries has some advantages for beginners. Keeps things simpler. Mishandling batteries with exposed terminals can create problems, or getting the wrong battery or a fake, etc. My everyday all day mod is the vtc mini but a brother of mine has been vaping almost as long as me and using an iStick 20 and an iStick 40 and getting long fine with those.
I'm doing temp control almost exclusively but I have an iStick 50 in good working order and the only reason I don't use it regularly is it doesn't do temp control. If I was using tanks I'd use it more often.Good and valid point.
I bought my first Istick 50 w because the advise and information on mods and batteries was so confusing. I got tired of all the contradictory advice and warnings, etc. It was making the gray matter leak out of my ears.
And to the OP, if you and the husband are looking to upgrade, why not try both, one for each? That way you can figure out what you like best.