Fully rigid chromoly is all that I have ridden, or will in the future.
My longtime main ride is a 1992 Trek 930 Singletrack, with significant upgrades. (Man, I love that bike!) The project I finished last winter and have been dialing in over the summer was built on a 1993 Rockhopper frame. That's a complete custom build and it turned out excellent.
I am of the opinion that the proliferation of suspensions was a marketing thing to promote bike sales. I don't disagree that suspensions are necessary for competition or trick riding, but c'mon. How often do most people go airborne (on purpose)? A rigid frame promotes good bike handling, and connects you to the road (conditions and feel) much better. And, I never have to ask how long my forks are going to last. (Forever.) I can go anywhere. There is never any concern "bombing down a hill" or taking a rough patch of downhill trail, at any speed.
Anyone that thinks they "need" a suspension may want to view this awesome video. It's fairly long - the first half is 100% urban riding, and in the second half they make it out of the city and into some serious off-road mountain biking, ending up literally at the top of a mountain. All on the same bikes, both of them rigid Trek Singletracks.
https://www.youtube.com/watch?v=uyrlEE9AV58
Or check out this one of Danny MacAskill, on a rigid MTB.
https://youtu.be/Cj6ho1-G6tw