Just to be REALLY pedantic...
Atari 600XL
Atari 800XL
They were fairly different form factor than the Atari 400/800 and came early/mid 80's, rather than late 70's.
One of the main reasons I bought my first Amiga is because it's a spiritual successor to my beloved Atari 800XL; in my very humble opinion a rather marvellous computer, which for me only had 2 major issues - games were more prevelant for the C64 than the 800XL and the main tape-drive units loaded programs VERY slowly (no 'turbo' load like C64) so games like Gauntlet would take over 20 minutes to load.
Still play "Rescue on Fractalus!" and "Mercenary Escape From Targ" on Atari 800XL emulator every now and then.
Yeah, I loved my Atari 800XL - nice machines indeed, though I damaged mine when I was experimenting with the parallel bus. Replaced it with another, and still have tapes and tapes of my programs up in the attic. I always found the C64 a little more powerful programming-wise though...
As for the Amiga, I think it's still thrashing around because it's still a little bit useable in this modern world. You can still use it for your IRC, email, MP3s, some light browsing, games etc., and with a modern screen. While there are some great communities still dedicated to the 8-bits, those machines live on in their own little niche and rarely participate in the modern world the way the Amiga can...
