Hands down, Salisbury Cathedral is my favorite gothic (1150 - 1500 AD) cathedral ever, it beats out Chartes. Chartes may have the best flying buttresses, but Salisbury is alive inside and still has a faithfull, active church community.

Durham is my fave romanesque (1080 - 1150 AD) cathedral. Granada wins for the Renaisance / Counter-Reformation / Colonial era (1530 - 1700 AD), although the Spanish early colonial militancy of it is a bit creepy. I have yet to go to a Neo-Classical or late Baroque church that I like, most of them leave me cold.

I have yet to get to any intact pre-1000 AD. The Church of the Naviety (Bethlehem) has been rebuilt too many times to qualify, and the Hagia Sofia (Istanbul) is no longer being used as an active church, although both are Amazing spaces. I will get to Charlemange's chapel (800AD) and to the Ravenna church (500AD), hopefully sooner rather than later.