I'm about to do the Citadel DLC again before I finish the game and yeah, some of the things definitely hit a more emotional chord now than they did then, like Mordin and his sacrifice.
I think Destroy is definitely the canon ending, but I wish that having a high Military Strength would make it so that it specifically targeted Reapers and not ALL AI, or if you resolved the Quarian War with peace between the Geth and Quarians that you could convince the Catalyst that Organics and Synthetics CAN live in peace.
Those two little changes I think would have bigger, and more satisfying, endings.
Someone also said that ME3 should've been longer, than it should have taken course over two games, one being the Cerberus plot, and the other the final offensive on Earth, and I kind of agree.
Either way, the trilogy can EASILY be adapted into, at minimum, 5 seasons worth of great content.