It's hard to say any season that didn't end in a title was the best, but I've never experienced anything like 89-90. They called it The Dream Season for a reason. It was an incredible journey the stretched over 6 months. Nothing was expected from that team. It had just lost it's best player in a long time the year before. The program hadn't even been to the NCAA's as a member of the Big East. In fact, I think they had only 1 BET win overall at that point. They play an incredible pre-season game to best the Russian National Team. A team that had beat everyone else except eventual champs UNLV. Their coach said UConn was the best team they faced. I thought it was just perestroika. A few weeks later, they throw up an absolute turd against Nova and we all thought we were back to the pre-NIT champ days. But then they start winning and winning and winning against the iron.
I was in Vegas the week before the BET and I was going to put a few bucks down on the Huskies and they were the 8-5 favorites! I say to no one in particular "UConn is 8-5?!" And the ticket seller says, "Yeah, they're really good this year. I think the're gonna win." A Vegas guy, picking UConn. WTF? They steamroll through the Big East, beating Coleman, and Mtumbo and Owens and Mourning while starting a one-legged center. We get the highs of the "Shot". You shuda been in the bar where I watched it. It was packed and at the end of the game, lifetime enemies were hugging. Of course we get Chrissie killing us, but before that we had Chris Smith hit a 3 with seconds left to send it into OT. That season had a sports lifetime of moments packed into it. IMO, that makes it the best.
My Top 5:
89-90
98-99 - 1st FF and NC
10-11
03-04
78-79 - Corny as a frosh, no Corny no Big East
94-95 (if Corny's year doesn't count as modern era)