Back when I was growing up and Star Trek seemed to be on all the time - so that's the late seventies and early eighties - the other shows I watched and loved included Doctor Who, Blakes 7, Sapphire and Steel, The Tomorrow People, Battlestar Galactica, Buck Rogers, and re-runs of UFO, Stingray, Thunderbirds, Joe 90 etc. I still love most of those shows - and indeed I'd regard Doctor Who, Blakes 7, UFO and Sapphire and Steel still easily in the top ten sci-fi shows of all time.
The weird irony (for me) is that I saw Space: 1999 (series 1 only) at the time of its original broadcast - and though I enjoyed it, I wouldn't say that I loved it, nor did it particularly stay with me as anything but a vague memory. I had a moment of total epiphany that day when I rediscovered it as an adult (25th April 1992 - seared in the memory!). I'd certainly now regard it as the best "space opera" type show ever made.