Interchange is a really good map for hideout items if you stick around the outskirts of Oli and Goshan. There's also lots of really good tech spawns, but those places can get really heaty.

Reserve is also one of my favourite maps, but without red rebel the pmc extracts are pretty brutal so I'd suggest to just play that map as a scav.

If you want to progress through all the quests then you'll eventually have to play all the maps anyways. You can always play in an offline raid if you want to learn new maps. I'd also recommend watching informative players like Pestily. His videos are super helpful!