I initially learnt to program 8-bit computers at school on a Research Machines 380Z, and progressed at home through a TRS-80, BBC Micro and Commodore 64 which for me was the ultimate home computer before the 16-bit Amiga came along.
The poll above is listed by brand mainly due to the ten item limit, and most home computer owners seemed to be more loyal than I was. There are some notable and not so notable omissions from the list so apologies if your preference is missing.
My vote narrowly goes to Commodore over Acorn, pretty much entirely due to the C64 SID chip, but it's a close run thing.
What was your favourite, and why?