Oh, one more I forgot earlier, if we're including "looks like fantasy at first but is technically SF because all the *MAGIC* is really just non-supernaturally-explained psionic stuff, also we have spaceships and computers": Christopher Stasheff's various "Warlock" series, which I gave up on at some point in the 1980s for getting too dull and repetitive, and a quick glance on Wikipedia says he's STILL cranking them out. o_O