You don't need anything but Fellout for Fallout 3, it's still available for Fallout New Vegas but there is much better options at this point. I think I am using something called "realistic weather and lighting" or whatever for TTW, all I know is that it preserves the look of Mojave while removing the green tint of Capital Wasteland while adding in rain, removing the eternal smoke/cloud over Pitt and Sierra Madre while giving certain areas their own weather effects(snow in Mt Charleston and upper area of Capital Wasteland, Tundra in Operation Anchorage, ect.). The only problem I have with it is that it has a broken perk that is supposed to make you immune to the negative effects of the weather(usually it impacts agility, sneak or perception if there is a heavy rainstorm)
For Fallout 4 I do indeed use Reshader, altho I never had any problems with it. Then again, I only use it to make nights actually dark so I don't think I used anything too fancy.