Usually "move" and "fight" are the most important stats in the game for the gang-members ... and imho in that sequence.
In addition an expensive fighter has not nessessarily the same increase in stats, so a cheaper one might do the trick, too. And if that unskillfull jerk (I knew that worthless moron couldn't pull that stunt, damn) gets himself killed, he is far cheaper to replace ... so if in doubt, get the thief!