@cwebber
I don't know that I can pick just one, but . . .
WordPerfect 3.2 with the little plastic multicolor guide that slotted over the left-side function keypad.
X11 with Motif widgets running on a GIGANTIC 19 inch Sun workstation monitor
The amber monochrome screens on an old VT420 terminal.
My old giant trackball from like 2004 that was about the size of a pool cue and a really comfortable hand rest.
The white 11 inch MacBook from like 2003.
The 2013 series of MacBook Pros. Flawless.
The golden age of Lenovo ThinkPads, including the little X1s that were such great little low power workhorses.
Flip phones. Seriously. My old ultraruggedized Casio flip was such a great device.
LaTeX's default typesetting output. I love that I can get it with Markdown and pandoc now.
ANSI animations and Operation Overkill II on BBS doors over a 2400 baud modem.
EDIT: OH. And workstations from like 1996-2004 that were super well designed for field service. Easy to open and service. LOVE.