Personally owned? Pick between TI57 in 1979 (8 floating point registers, 50 bytes of program space) or Apple IIcx in 1989 (16 MHz 68030, zero RAM, zero HD at purchase .. I added my own 3rd party of each. Anything from 1 MB - 128 MB RAM was supported).
Used: HP97, TI58, Burroughs B1800, PET, TRS-80, Apple ][, PDP11, VAX, Macintosh, DEC Rainbow, Sanyo MBC555, IBM 5150, DG MV...