User blog comment:Chaoswolf75/What's the hardest choice you've had to made throughout the series?/@comment-70.143.83.247-20120715070848

The Heretics was a big one: free will and genocide vs subverting free will and promoting plurality.

Virmire was easy once I played through a second time and realized that Kaiden is just plain more likable then Ash, the endless whiner. The first time through it was easy too thanks to the always save the girl mentality.

And for the second fireteam I used Grunt, of all people. Then I looked up this wiki and loaded a save...

No the tough decisions were in the purposefully flawed playthrough - engineering it just right to kill off Thane, Jacob, Miranda, and leave Zaeed to burn without losing any of the likable characters.