I usually use Deathmatch for aim pracctice, but there are also several maps on which you can play when you have no internet, for example aim_botz, aim_map and aim_redline. The rest of the time, I play Deathmatch servers with different weapon types such as pistols, smg's, rifles! Please note, that the names of the maps are clickable.
On Aim_Botz, you can easily counter the enemy by using the boxes which the current map gives you as an advantage, that's a cool thing about the map since you can use different types of distances for enemies just by clicking several circles inside the spawn. You can make the bots either move or stand still, change speed of their movement or several counter-strafes AD-AD.
Aim_map is used usually for aim-practice between teammates or friends (which i usually do). But the map can be used good with bots, as well, thanks to the distance and the ability to position the enemies (bots). The texture of the map is good, too, because you might see similar boxes or positions during real matches.
On Aim_redline, you can practice headshots, because the distance is bigger than usual, and the opponents are peeking behind boxes, so you can see only their heads. It is a good map for the AK+USP combo, at least that's what I prefer to use it for.