Grind - I love the oddly shaped barriers and objects. It stops people from head glitching. I also love the middle area with the little 'window' where shit is always going on. 9/10
Mirage - This map is mediocre to me. I can't remember anything exciting going on while playing this map. It flows good, but nothing spectacular. 4/10
Downhill - This map gets the least amount of playtime out of the pack. It is pretty fun, and feels like Discovery from BO1. The hills of snow, and the little buildings make this map interesting. 6/10
Hydro - This is my favorite map out of the pack! I'm not sure why everybody hates it, I always have great games on this map with tons of kills. The simplicity is what I love. Most of the action happens in the middle without too much flanking. 10/10
COD4 10th Prestige 55. My favorite COD.