I only plan to invest in one faction. I cannot afford to have all the things like I have historically done with xwing (and if I get Legion I need to adapt that spending habit, but I digress). That said...
Would you rather buy your faction, keep the other side of the core set “just in case” you need stuff for friends to play (and do only core set battles at that point, saving expansions for other friends). OR, trade the opposite side of the core set for more corps and support and get my army built faster, but only be able to play against people with other armies?