This first one zm_facility_final would be best suitable when the player count is low around 15-20 https://gamebanana.com/mods/88340 size 2.48 MB
Second one zm_laboratory would be best suitable when the player count is 24 to 30 ~full https://maps.cs-bg.info/maps/cs/3428/ size 2.79 MB
3rd one zm_mygame_mountains is a bit unique than the rest of the maps suggested here , it is a mountain themed map with alot area , would be best when the server is full https://www.gamemaps.com/details/12475 size 1.8 MB
4th one here zm_titan is a city themed map with alot of area and tall buildings best suitable when the server is full , this map would be very good to strafe in for both zm and humans https://gamebanana.com/mods/89059 2.25 MB
Hope you guys like the maps