Damn, I like all three candidates. Wouldn't Tsongas be closer ideologically to Brown than Clinton? All three were running under different types of "fiscally conservative socially liberal" as I recall. Not an easy choice.
I was only four at the time, so my knowledge comes form what I read, which seems to imply Tsongas is closer to Clinton. While all three seemed to have run as social liberals/fiscal conservatives of varying types, Brown is also described on wikipedia as having "a significant reform agenda, including Congressional term limits, campaign finance reform, and the adoption of a flat income tax."