Personally, I've only used Windows 95, 98 and XP, which I thought were all pretty good (they seemed stable anyways). The Windows 95 machine ran at my parent's house for 7 years (1996-2003). The 98 machine was 1998-2004 (maybe 2005). Windows XP was 2003-present. They may not be perfect, but they turned on and off when they where supposed too.

My brother got to tackle with Windows ME, he couldn't even say that much about his system. When a computer in perfect working order only turns on most of the time...something's terrible wrong with that OS.