I've got a slew of recommendations that, in some fashion, fall into the Sci-Fi genre:
Silverhawks
Biker Mice from Mars
He-Man
She-Ra
Digimon
Lion Voltron (either the original 80s dub , its 3D sequel/continuation series The Third Dimension, or the forthcoming series Voltron Force, which doesn't premiere till next spring on Nickelodeon)
M.A.S.K.
Transformers: Beast Machines (the sequel to Beast Wars: Transformers, and which I actually enjoyed more than its predecessor)
Robotech (the American dub of Macross from the 80s)
C.O.P.S.
I wouldn't apply the label "high quality" to many of those.
Silverhawks in particular was awful, a ridiculously silly premise. It,
MASK, and
COPS were basically just about selling toys.
As a Filmation buff, I want to praise
He-Man and
She-Ra, but while they were a little ahead of the curve in some ways for their period, they're very much kids' shows and tend to be repetitive. They're largely about selling toys too, though they occasional rose above that to some extent thanks to writers who had bright futures, such as J. Michael Straczynski, Michael Reaves, and Diane Duane.
There's not much else on that list that I was actually fond of. I liked
Beast Machines, but not nearly as much as
Beast Wars.
Robotech was pretty good, and is the only show on the list that wasn't primarily targeted at kids (at least, the anime shows it was based on weren't, I don't think), but it's often criticized for its extreme departures from the originals.
Of the things mentioned there, I'd give my highest recommendation to season 3 of
Digimon, or
Digimon Tamers as it was known in Japan. That season -- that incarnation of the concept (each season after the first two is in a separate reality and continuity) -- was the oldest-skewing of the bunch and the smartest. It was written by the creator of
Serial Experiments Lain, one of the most brilliant, bizarre, and mindblowing anime series ever made, and though it's still geared toward relatively young audiences, it gets into some pretty intense areas. It's also the most science-fictional and least fantasy-based incarnation of
Digimon.