I seem to recall posting on a similar thread like this in the past but didn't notice my two cents in this one so here goes.
Everyone always seems to miss some of the best titles ever on the Amiga when they compile these lists. These are the ones I recall wasting
way too much time on. And I recommend each of them if you don't already have them!

TV Sports Basketball (Cinemaware)
Wayne Gretzky's Hockey (Bethesta)
Empire
The Perfect General
Turrican
Battle Squadron
Railroad Tycoon
CIV / Sim City / Populous
Settlers
Syndicate
Dungeon Master
Pirates!
Just about anything from Microprose before 1991 was invariably a great game (best combat sims etc in the day).