BBC Micro - best 8-bit computer of all time
Although Apple set the standard years earlier with the Apple II, the BBC Micro trumped it and all other 8-bit computers ever made by having the best hardware, OS and BASIC interpreter of its class. Sort of a "UK Mac" for the early 80's if you will and it wasn't until the Archimedes came out in 1987 that the technical prowess of the BBC Micro was finally beaten (yes, I tried an early Mac, but it felt quite straitjacketed even back then).
I helped out in a computer store in the early 80's and saw pretty well every type of 8-bit micro that was going then. Spectrum had the most games obviously, but its keyboard, graphics and sound were so poor as to be actually embarrassing to use. The Commodore 64 probably came closest in terms of hardware to the BBC, but was hugely let down by its poor OS, BASIC and utterly dismal disk system (so slow, that it was beaten by turbo tape loaders!).
I think that the BBC Micro was a perfect design for going into schools to replacing fairly doddering RM 380Z's and the like - its strength was indeed the OS and BASIC - the built-in assembler was a stroke of genius and you could actually develop commercial code on the same machine you ran it on (note that many Spectrum programmers - think Manic Miner and the like - used TRS-80's to code Spectrum games (downloaded via some clever add-ons) on because the Spectrum itself was a disaster to code commercially on.
The crying shame that was overpriced and never actually came down in price during any time in its production run, which ultimately was fatal to it. A drop of 100 quid would have probably doubled its sales. The Electron was horrendous - who wants a machine with no Mode 7 and half the speed of the BBC, especially when it was launched when pretty well everyone who wanted something in the BBC Micro range already had one.
I also felt Acorn were terrible at marketing - you'd hardly ever see ads on TV or print media for it, whereas Spectrum ads seemed to be everywhere. The Spectrum may have been significantly worse in almost all respects except the amount of RAM (the hardware was shoddy, it was slower, the OS and BASIC were simply dreadful), but Sinclair knew that once he got game developers on board, the cheaper machine would win out, even if it was basically a piece of junk.
My path went BBC Micro A, added RAM, added disk interface and disk drive, added speech chip, added sideways RAM (very handy for, er, running ROMs from disk)...then about 5 years later, jumped to the Archimedes A310, which I never bothered with a hard disk because it booted from ROM and 3.5" floppies were quick enough for me at the time.
Loved the Archimedes hardware, OS and BASIC again - a tour de force of engineering, the ghost of which lives on in most mobile phones as the ARM chip of course. Built-in assembler and a module loading system to add functionality, plus a reasonable WIMP for the time (perhaps not as good as the Mac's, but certainly better than GEM and Workbench) combined to make it a dream ARM development system.
It took many years of Archimedes use before a generic PC with Linux finally overtook it both in terms of speed and functionality - yes, I've never used Windows as a primary OS in all that time, though I do it run it via dual boot or VMs occasionally.
The 80's were the golden age of choice in the UK, but the 90's brought us the "one PC fits all" of Windows 95, the "nice but overpriced" of Macs and very little else (Linux really did take a long time to get the distros to be easy to install and use, but now they are technically by far the best OS to use, particularly if you are a developer).