I love the HP 1000 mini's, specifically the original 'family of three', the
2116, 2115, and 2114.
I'm no fan of the 2100 though, and don't care much for the M-series.
But the E-series and F-series machines are very nice indeed!
In addition to HP mini's, I've also got a soft spot for vector graphics, like
the Imlac PDS-1.
Combining these, I'm also a huge fan of the HP 1350 / 1351 vector graphics
hardware, and the HP 12555 series oscilloscope point-plot displays (I drive an
original Tektronics 611, I found 'new in the box').
On the HP systems, I enjoy tinkering together hardware interface projects like
tape reader and punch emulators, IDE disk hacks, etc.