There's lots of mods created that add new content to the games. There are mods that add new perks, areas, and quests.

So far, I know of the following that add new quests and a lot of content that I tried in the past:

-Alton (a new world)
-Vault 101 Revisited (ability to return to Vault 101 after completing Trouble on the Homefront in Amata's favor)
-Point Lookout Reborn

Perk mods that I've tried:

-Ultimate Perk Pack

What other mods are there that add new content that are recommended? Should I use any of the mods above that I've listed?

Which Fallout are you asking for?

3. I guess I should have made that clear in the title.

F3 didn't get many DLC-sized/large mods, and the stuff there is (like Alton) is super amateurish. It's probably the Fallout with least amount of sizeable mods