Coliseum and EG are pretty much tied at first for me, I don't pay much attention to what the boss drops in EG are so it's hard to pick a favorite but I figure EG is at least getting me more rewards drops (just not sure if they're as good). In EG if you have high SED and event cards you'll pretty be 1 "weak" hitting everything until the very end of the halves or the SEGs. Gambit unfortunately doesn't amount to the same amount of "good" rewards since a lot of the briefcases also drop items like and radars, glasses, or whatever the item we're suppose to be collecting is which is not useful after the event and really doesn't make much of a dent in the "Collection Achievement Rewards" of these Gambit events. Although it's still nice you can progress through Gambit stages really just based on stamina, I don't feel like I'm falling behind as much if I only log in once every 8 hours.