don't take this the wrong way, because this is me talking about "us", not you, but "tech" is such an interesting word in this context. A lot of the time we can infer what it means from context, and it almost always means "shit with transistors, probably made after the walkman." but here you've deliberately given me an unlimited lower bound on how old it can be and that makes it complicated.
I have a 1969 Sears mechanical calculator sitting on top of a cabinet upstairs. Would I prefer to use it over an electronic one - no, absolutely not, it's slow and the interface is awkward and it's hard to read. But is it useful? Sure. It still does basically what an adding-machine type calculator does, and those are still sold in stores and still quite useful. Given that your input rate to those devices is usually limited by the time it takes to refer to other printed materials, the low speed doesn't really matter that much. And it's still "tech." Hell, it even runs on electricity.
I was going to follow this up by trying to actually answer the question but... honestly, I don't know that I have an answer. You know what the dirty secret is about me? I hate all this old shit, and a lot of it I hated when it was new, because it wasn't perfect, wasn't ideal.
Every piece of technology has an intent behind it, a vision of a utopian future where Problem X is Solved, where our receipts get added up just by us thinking about them, and UI and UX and input speed and output format don't matter. Every adding machine, every abacus, every tally stick was made with this vision in mind. The Chinese guy 1000 years ago, carefully chiseling filigree into a hunk of ivory that'll later be used to authenticate a military order - the whole time he was thinking, "if only we could do this without all the chiseling." And eventually it came true, and now nobody wants to use the fu; even if it's still notionally as useful as it was when new. everyone would prefer to send an encrypted email.
It bugs me that Windows 95's notepad doesn't have a keybinding for Ctrl+S; they added that in 2000 or XP. I depend on it so deeply that editing text files on Windows 95 is a miserable process for me, I'm constantly tripping over my own shoelaces using that thing. The point being, I could pick stuff that one could, arguably, use - but I can't easily think of anything that's just as good, let alone better, than something we make now. The exceptions are things we don't make anymore, which... I guess that topic frustrates me so much that I can't even come up with a list at the moment.
