I sided with NCR simply becouse it has most quests and backstory in game; You can end almost every mayor quest rightfrom the start aiding their couse. Yes Man told you in his finale that he intend to be asertive in the future - going skynet and Mr House is like God Emperor from WH40K or Dune dicator who will rule for ages; Judging from Strip and Freeside I'm not impressed so No thanks. Ceasar lack quests (and charisma too ) and his line devolves into mindless sloughter very cartonish and chaotic stupid in style. Pitty since he had a good start in Nipton; acting as frumentari demoralising foes and gaining alies throu deceit more than sword woud be intresting. But someone had to replace Enclave as an absolute Hitler like evil. So I backed the corupt and inaficiet political system for lack of better alternatives; I'll play second run after solid patches and Legion DLC.