Civilisation seriews
The Civilisation series is largely responsible for my interest in turn-based strategy games. I started with Civilisation and progressed to Civilisation II, but not much further. I felt the subsequent games were not addressing the issues I had with the first two.
Civilisation II (including Fantastic Worlds and Multiplayer Gold Edition)
Pros
Good fun
The basis for what my perfect turn-based strategy game would look like
Cons
Unequal diplomacy
AI doesn't build enough cities, improve enough land, attack well or defend well
Random game generator lacks ability to set number of starting cities and tech level
Civil disorder - pandering to the needs of fictional citizens is not my idea of fun
Too much pushing units around the map, the following should not be unit driven: espionage; exploration; terrain improvement; trade
Unrealistic terrain improvement (tundra can be transformed into grassland and then has the same agricultural productivity as tiles in a temperate area. No account taken of climate)