For me it's the 1991 first round playoff matchup. I was certain we were gonna slice up the North Stars especially after Roenick opened up Game 1 with a goal like 30 seconds in, but then the Stars ended up beating us that game and won the series in 6. Bad times for Hawk fans that year.
Was in college in LaCrosse, WI from 89-93 and me and some fellow Hawks fans went up to about 20 games up there over that time.
I was at all three games in 91 up at the Met Center. Game 6 is the worst/most disappointing sporting event that I've ever been at. We were in row 2 down by the glass with our jerseys on and had to make the walk of shame after the loss with all their fans taunting us. How we didn't end up in jail or dead, I'll never know.
Still hate hearing the song Rock 'n' Roll Part 2, which they played over and over. They used to play the intro to Welcome to the Jungle SUPER LOUD (paint peeling) at the start of a power play - which was actually pretty cool.
I realize that most Hawks fans don't/didn't see the North Stars as our biggest rival, but my personal experiences up at the Met Center caused the North Stars to be BY FAR one of my most hated rivals in any sport and continues to fuel my hatred for the Vikings (I'm a Packer fan) and Gophers (I'm a Badger fan living in Madison & WI for 24 years now).
At the Met Center - We got into a couple of fights - trust me, not instigated (but not avoided) by us. Got threatened in the restrooms. Got rocked back and forth in a Porta-potty in the lot - which was actually funny once the terror subsided.
Got thrown out after a buddy of mine got hit by an ice cube in the face and then dove into the row where it came from which almost caused a riot. We were in the lower seats and the food and beer that rained down from the upper seats was super thick. Luckily, I was already in the concourse with another guy, not knowing what was happening behind us. We're like "should we go out there?" Nah!
In addition to all that, the Hawks were TERRIBLE up there during this era or at least when I was there. Saw like 4 wins out of those 20 or so games.
Despite all of that, I was super-bummed when they moved. I love having hated rivals and I don't feel that way about any other Hawk opponent although Vancouver is sorta similar.