If you are interested in sphericals then SA is your only other option. And as you've noticed, they are not easy to acquire. You have to get in on the group buys when they happen (and then wait many months to receive them) or hunt for used sets. Unfortuantely, they rarely come up for resale, and when they do they get snatched up fast.*
If you are interested in cylindricals then I can't help you. I don't use them. But the suggestions to go with GMK or Cherry are the most common I read here.
* If you do go hunting for used SA sets, you probably want to look elsewhere. When it comes to used keycaps, the geekhack classifieds forum is basically a marketplace for artisans and little else. Used SA sets occasionally pop up but that signal usually gets lost in all the noise. You'll probably have better luck watching in the Deskthority Marketplace forum instead.