I feel like GAS slots into more teams. Great with clones, Padme, JKR, GL Rey, and I hear he's good with JKL (hope to find out myself later this month.) Basically if you are running anything light side except rebels he has a place. Malak is a monster, but maybe a little more limited these days? I only really use him with Drevan, and I see him on GL Kylo squads but he is by no means a must-have for that team to work. So it depends on what fits your particular roster best, but I think GAS is more versatile.