I linked my other collection for maps that I have yet to play, but think could have potential to be added into this collection.
There aren't that many mods yet sadly, but there are some amazing ones released that'll guarantee more fun on classic treyarch maps, custom zombies and/or multiplayer! Anyway, hopefully this will help you get custom maps (this collection will be updated) easily without having to go through 1200+ maps in the workshop. Hopefully in the future there'll be more creators who can and are willing to work on a map for a longer period of time to make it epic. So far there isn't that many, only something near 150 custom maps that're even worth looking at(in-game).
This is a collection of, what I personally believe, are the best Custom Zombies & Mods in the whole workshop.
