I loved Mass Effect 3's multi-player despite expecting it to be horrible, but it was also the first game I really enjoyed that had such horrid lootbox mechanics.

ME3's single-player was a masterpiece until the last hour. I didn't even necessarily hate the endings. I just hated that in the end no matter what had happened, it came down to "pick the ending". I would have been much more satisfied if your actions throughout the trilogy had determined the ending you got - especially since they had done so much tying together loose ends from the previous games.

I loved that you could actually save both the Geth and the Quarians, but only if you'd made the correct decisions in Mass Effect 2 AND 3. That same kind of logic could have been used to pick the ending.