No, I believe that would be Alien Nation.Fun show, am I wrong in thinking that it started the Fox-Cancels-Beloved-Scifi-Show trend that continues to this day?
Well, first off, FOX brought back Alien Nation for a series of reunion movies. They may have made the choice to cancel it for financial reasons (because they wanted to expand their lineup to more nights and they could produce four sitcoms for the same cost), but they nonetheless believed in the show and wanted to find a way to bring it back, and they eventually did.
Second, it doesn't "continue to this day," not in the sense implied. The executives running FOX today are completely different people from the ones who ran it when, say, Firefly was on, and they've shown they're willing to stand behind their genre shows and give them every chance.
The bottom line is, most TV shows get cancelled young, period. It doesn't matter what network or what genre -- putting a TV show on the air is a risky proposition, and most attempts will fail within the first year. Genre shows are particularly hard to keep on the air because they're more expensive to make and tend to draw in narrower audiences. So it's always a gamble, and most attempts will fail. The real reason FOX has cancelled so many genre shows is simply that it's bought so many more genre shows than any other broadcast network ever. So it really gets an unfair reputation.
As for Brisco, I'm not sure how "beloved" it was, really. It's got a cult following, but mainly because Bruce Campbell has a cult following. I don't remember it having the same kind of devoted fanbase at the time it was on that, say, Firefly did.