I have 3 favourite maps, listed in order:
Grain Elevator
This is a very diverse map, and tactically very interesting. Both sides can have the upper hand in an instant and I've had my best matches with furious fighting on this map. It has something for everybody in it, not least it's an interesting layout.
Spartanovka
A bit of a rifle map rather than CQB (as a rifleman, I am happy with this). There's lots of room for tactics and squad co-ordination.
Apartments
I might get flamed for having this as my 3rd favourite, but I love the flow of it and I like the combat in Propaganda. Not so hot on the park area, but the rest is great.