I ran into this issue, and finally zeta'd Boba yesterday. I was pretty much in your situation -- QGJ and Boba were my only currently viable options, everyone else needed work. Moreover, Vader and Barris (my two likely other choices) both require carbantis, which Shoretrooper needs (and is my current gearing project), so they aren't going anywhere for a while. So I sat on my zetas until I hit 40 yesterday. The reality is that, whomever comes out, with the most game-breaking zetas ever, will take a sufficient amount of time for me to gear that I'll accumulate another full set of zetas by then anyway.
I chose Boba over QGJ, because Boba is currently on my arena team, and I don't have GK yet, or Aayla, so a good Jedi team was not really in the picture.
