For other games with large modding communities Nexus Mods is often not the main site.
My favourite modding setup I have seen has to be Thunderstore with r2modman (initially Risk of Rain 2 modding, branched out to other Unity games), ridiculously simple and functional. All FOSS too.
Another good option, but more than two is better than just two giant ones.
For Bethesda RPGs: afkmods.com, tesalliance.org, loverslab.com (NSFW but has normal mods too). There are a bunch of small sites like these.
For other games with large modding communities Nexus Mods is often not the main site.
My favourite modding setup I have seen has to be Thunderstore with r2modman (initially Risk of Rain 2 modding, branched out to other Unity games), ridiculously simple and functional. All FOSS too.