For my money, the only show that was in the same category as Star Trek, up to the late 70s, was the original Twilight Zone. Most other sci-fi offerings, though fun, were cheesy and well, not top-notch.
Agreed, although I think the original OUTER LIMITS deserves an honorable mention. It was considerably lessy cheesy and juvenile than, say, the Irwin Allen shows. At its best, say, "Demon with a Glass Hand," it rivaled TZ.
And I admit it terrified me as a kid . . ..