Now with a month of reflection:
I'd say it's a toss-up between the 03 Sox (I was too young to remember 86) and this Pats loss, but I think its just this Pats loss.
With the Sox, at least I could rationalize it as the Sox being the Sox, and it was just part of a long history of heartbreak. Don't get me wrong, it was a brutal feeling, and I can still remember what it was like to be hanging around Boston in the hours after the Boone homer. Brutal, just brutal. But with Brady and the Pats, you expect them to win - and at this point, everyone hates us, and our only defense is winning. 19-0 on the line, all that, all the plays that could've gone our way, I think all that adds up to this one hurting more. It's been a month, and yet thoughts of the game pop-up quite often - too often - in the day, I immediately get pissed off and have to start thinking about something else.
They are both traumatizing losses, but I give the Pats the slight edge right now. Ask me again in a year after we've won the Super Bowl.