Sure Marvel did a decent Star Wars comic back in the day. But they also did a good Warlord of Mars comic then too.
But Marvels recent attempt at a licensed John Carter comic were nowhere near as good or as fun as the unauthorized versionss from others.
A Princess of Mars: A Graphic Novel, Adapted by Ian Edginton and illustrated by INJ Culbard. A great, thoughtful adaptation, of Burrough's Princess of Mars. So far beyond what Marvel's officially licensed book. I can't recommend it enough.
And Dynamite's Mars comics were so much more fun, not only is it still being published, but it inspired spin-offs, that are still being published today! there is even a current miniseries is crossover with Tarzan. And if you are a big fan of Joe Jusko, the man responsible for so many great painted Savage Sword of Conan covers and many other painted covers for Marvel publishing endeavors back in the day, you can find him now painting great covers for Dynamite's comics, including many Tarzan and Mars comics!