I have a max Biggs, and in a short answer no- he is not a gs or a QG.
It's important to note he is not an attacker, but a support character, also he has a relatively poor attack for an assister (slightly better than Fives).
However, pair him with the Rebels and Rey and you're onto a winner, for example Ackbar(L),Han,HRS,Rey,Biggs. He will shine in this composition as a perfect support attacker to HRS and Rey.
If you're looking at damage output alone then you aren't using Biggs like he should be used, and you should look for an alternative.