The A1000 was way ahead of its time in 1985, and that was still true
with the A500/2000 between 86 and 89.
The A1200 was anice speedup for the Amiga-freaks, but it was allready
failing behind in many aspects.
It only had 2mb of shared (slow) memory, while PCs could be brought up
to atleast 4MB (often 16) by just adding the ICs/SIMMs. And all of that was
running at full CPU-speed, and non-shared.
A HD-floppies were allready standard in PCs, while it required obscure and expensive
modified drives for the Amiga.
A HD was also standard in PCs, and could easily/cheaply be bought.
The A1200 only supported expensive and small 2.5" HDs. The adapters
to 3.5" only appaered in spring 93, and they still costed extra, and not all 3.5"-HDs
would worked with the A1200.
16Bit-Audio was also not uncommon in PCs of that day.
And a bog-standard VGA would crush AGA for everything but 2D-games.
You are right about the OS.