#1, and still #1 in my <3, Radio Shack MC-10
The coolest thing about it: Expansion connector on back, which on mine went straight to a home made circuit board with extra memory, a 6821 PIA and a breadboard.
Followed that with Radio Shack Color Computer, several CoCo 2's and a CoCo 3.
My father had started a logistics business from our home and we ran everything off these machines. CoCo Disk controller supported 4 SSDD drives, we used to take a pair of DSDD's and "split" them by attaching drive select lines to head select with diodes. Gave you a whopping megabyte of storage. Did dispatches, routing, scheduling, AR, AP, messaging and telex with these until 1986 when I built him an XT clone. I eventually ended up with a network of 386's, but even then the CoCo's were still around to send telexes and dispatches.
All my other computers were PC clones, but I never bought a branded box, always built.
Clones are the ultimate green PC's. I went XT, AT, 386, 486SX, 486DX, 586, P200 MMX, AMD 2200+ with only 3 cases, 3 monitors and 2 keyboards.