I'd generally say "easy as pie" if the discussion is just a matter of everyone's kind of adding their own two cents (or fifty cents, maybe), and that's kind of it.
Whether it's online or off, I'm pretty much never about "the last word"; but if there's a civilized and "legitimate" discussion, and I have the time and/or interest (and someone else has the time/interest) in having a discussion beyond just "everyone adding his two cents to the matter"; I do enjoy a discussion regardless of who has what opinions. That's CIVILIZED discussion, though - not bickering and name-calling and complete and utter disregard for reasoning, or at least "giving reasons".
All that aside, it's actually easy as pie for me to leave the second things in a discussion start to get unreasonable. So, I guess, one way or another.. I'd still select ":easy as pie" for one reason or another.