Don't you dare say it's worse than ME3's. ME3 has the sense of finale and climax and tonally I think it's good, but it just doesn't make enough sense, it subverts the antagonist at the 11th hour in the cheapest, dumbest way I have ever seen and then derails the entire narrative by pulling up an entirely new theme (will our creations ever rival our intelligence and eradicate all organic life?) and resolves it... in the final 10 minutes of a 90 hour story that was never clearly about said theme.
DA:I has a logical followup.
Premise: The death of the divine causes chaos and uproar and it created the Breach. We must close it, find those responsible and bring them to justice.
Ending: The Breach is closed and its mastermind is killed and the peace is restored, for now. A new Divine was elected. All's well that ends well.
Mass Effect 3 has... ugh, I just have no words:
Premise: The Reapers, large killer-machines who harvest all advanced life every 50k years have invaded the galaxy (EARTH!), we must stop them in order to survive (we retake earth to... to... to WIN THE WAR, YEEEAH! (psst! Retaking Earth is just delaying the inevitable when Reapers are everywhere else, but nevermind that! Marketing and CoD appeal!)
Ending: "Synthetics and organics will never get along" (except for EDI & Joker, GETH AND QUARIAN!!!) so the protagonist solves the issue by making 1 of 3 choices - all very vague in function because Bioware hates detail - that will solve the problem through implausible methods of magic or he will sustain the issue by just killing the Reapers and reaper-coded synthetics like the "True" Geth and EDI or let the issue hang up in the air by ASSUMING DIRECT CONTROL of the Reapers... oh and this also ends the Reaper threat... just a minor detail, because... well, you know: "Synthetics will ALWAYS destroy ALL organics!"
DA:I's ending was meh, which according to Bioware 2013 is actually the worst kind of feedback they could've gotten, unfortunately.
ME3 on the other hand... oh, hohoho, was just beyond terrible and Bioware said they're happy that it wasn't "meh" to even those who disliked it.
So I guess ME3 wins?