Do the Allied Space daily for the commendation and Battlezone for everything else.
Though honestly you could skip the Allied Space daily if you wanted to - you'll easily clear the 350 marks needed to get 5 commendations doing just Battlezone. I do the Allied Space one myself because I enjoy the space zone and because I'd prefer to use those excess marks to generate even more dilithium.
Just do the Battlezone for everything. It gives you a commendation for completing the 2 cap points mission.
Been doing battlezone. Spend a couple hours there one night, got the daily commendation plus enough marks to pay for 15 more (plus a couple days worth of dil besides). Did that three times and now its just a question of waiting on time gating till I'm T5.
Even better, for my other characters, once the first one gets T5 and can do sponsorship tokens, the rest can get enough commendations in one night's play to get to T4 and get all the passives. Hell of a lot easier than running the queued events over and over.