It certainly was more stable.
Sorry, given the wide range of hardware, drivers, and software developers, Windows was probably the least stable compared to Mac or Amiga. The flexibility and expanse of hardware was at the cost of stability due to poor drivers, conflicting hardware and an OS that did not separate such things yet.
It was not until Windows XP that MS brought the stability of NT which the driver availability of 9x.
*I think the preemptive multitasking feature of AmigaOS is mostly overrated.
No offense, this is probably because you have no idea how it really works, how hard it would be to code something like this given the specs at the time, and have no idea how bad the other systems were during that period of time. Remember, by 1985 Andy Hertzfeld was just beginning to shoehorn Switcher into 512k Macs (which would lead to MultiFinder).
The biggest advantage the Amiga had was multitasking was built into the OS...it was part of the framework foundation. Most of the multitasking that came after the Amiga was an afterthought so it was never part of the foundation. It became a layer that the OS and Applications had to pass through.
This is one of the reasons memory fragmentation could really cause 'multitasking' to have problems on say Switcher, MultiFinder, or even early Windows. The Amiga was created with multitasking so memory fragmentation was not a huge problem.
As an adult, programmer, and CS Professor, I would love to sit down with Carl and ask him many questions about his designs. Knowing what I know now, he was a bigger genius than most people realize given what he had to work with.
-P