I'm sure this is a common one, but weldments is one of my favourite features of SW, which I am currently porting across from.
To be able to build a library of common Aluminium and steel profiles and easily allocate them to a 3D line structure, and to be able to output a cutting list (with angles) would be a great boon.
Fusion 360 could also improve on SW joints options if this feature could be added