The Alpha port made it through to early release candidates of Windows 2000, and somebody is using it, because there were PuTTY builds for it.

I’m pretty sure the PowerPC port of Windows NT was the least used. It was the first to be discontinued, at least.

I've seen live Alpha installations of windows NT driving RIPs at large format printing shops in the 90s. It was also not unheard of at VMS shops.