I found it playable enough on a 33Mhz 68030 with AGA. If Doom had come out for Amiga in 1993, 68030 accelerator sales would have gone through the roof and Commodore would have probably sold enough A4000's to keep afloat. This was well before the days inexpensive home build PCs. Instead many people went to Time UK or wherever and paid over a grand for a PC to play Doom.
I was building PC clones well before Doom. If I recall correctly, I first played Doom on a 386DLC-40 system that I had built. It wasn't until I upgraded to a 486 a couple years later that it really ran well though. Maybe it was different in the UK, it seems the Amiga was much more popular as a home computer there. I only ever knew one person who had an Amiga and that wasn't until the mid 90s so it was an old computer.