AmigaOS could have competed with Win3.11 (when it would had RTG support and came together with more professional hardware)
I don´t consider Windows 3.x as competition.
It is really interesting how low were expectations for professional OS in the early 90s. I still use Windows 3.1 regulary (I wrote most of my school work on my 486SX notebook), but it has severe limitations (eg. 8+3 file names ).
It is clear that OS is not important, applications are what matters.