Most Amiga users - at least the home computing/gaming enthusiasts - never saw a big-box Amiga back in the day. To most users, 'The Amiga' was the A500, which released in '87 and reached peak popularity in the very late 80s/early 90s.
And to most Amiga gamers, Doom was where it became clear the PC had overtaken. Amiga game developers also got obsessed with trying to build a Doom clone for the Amiga, repeatedly showing how futile that effort was* , and much talent was wasted in that pursuit rather than making more good 2D games.
But by the time Doom arrived, the SNES had already been out for a couple of years, too, and despite a weak CPU it absolutely destroyed the Amiga in terms of 2D graphics performance (multi-layer parallax, loads of sprites, loads of colours, and 'Mode 7' effects)
(*ok, maybe not entirely futile if you've seen Dread/Grind which are super-impressive, but it took until the 2020s to pull it off, with an engine that seems about halfway between Wolf3D and Doom in terms of capabilities)
Eh. When I saw the Macintosh II demoed in 1987 compared to my Amiga 2000 which was released at basically the same time, I already knew the Amiga was screwed.
Looking at the UIs for early Macintosh vs. Amiga Workbench it feels like Amiga didn't put much thought into aesthetics. Just look at the color scheme they chose for the desktop UI:
It seems they had at least 64 colors to choose from and they went with... Orange and white on blue? They also decided icons should be able to be arbitrary sizes for some reason, a feature I haven't seen in other GUIs.
Here's workbench 2.0, which is better but still pretty unappealing.
That color scheme was allegedly picked for visibility on very low-end TV sets. (The Amiga palette colors could be chosen arbitrarily from 4-bits per channel RGB, so that wasn't a constraint.)
(The icons weren't just arbitrary sized, they could have different pictures for the selected and unselected state. You see this with the open vs. closed drawer icons (drawers are like "folders" in other OS's) but many app icons also used this effect.)
Be that as it may, if you look at C64 GEOS which ran on consumer TV sets and with comparatively primitive hardware, the UI looks so much nicer in GEOS to my eye. Even the Apple II GEOS makes Workbench look like a hot mess.
There weren't any 'default' icons, so the workbench didn't show you everything on the disk, only programs with ".info" files which had the icon. You had to drop to the command line to do most low level things. Of course, Workbench didn't really matter when you were playing games.
There was an option to show everything - with default icons. (Not very useful ones since notions of document ("project") file types were not used all that much, so every file showed as some sort of executable. But the option was absolutely there even though it wasn't the default.)
At the time though it didn't seem any worse than the Mac though, and it had colors - even if the defaults weren't great, any colors seemed better than none.
Or at least that was how tasteless teenage me saw it.
The Mac barely survived Wintel, so its not that apt of a comparison. If Microsoft didn't port Word/Excel over, I don't think we'd have many options now.
And to most Amiga gamers, Doom was where it became clear the PC had overtaken. Amiga game developers also got obsessed with trying to build a Doom clone for the Amiga, repeatedly showing how futile that effort was* , and much talent was wasted in that pursuit rather than making more good 2D games.
But by the time Doom arrived, the SNES had already been out for a couple of years, too, and despite a weak CPU it absolutely destroyed the Amiga in terms of 2D graphics performance (multi-layer parallax, loads of sprites, loads of colours, and 'Mode 7' effects)
(*ok, maybe not entirely futile if you've seen Dread/Grind which are super-impressive, but it took until the 2020s to pull it off, with an engine that seems about halfway between Wolf3D and Doom in terms of capabilities)