Fallout for it's lore, Metro for it's visuals.
Honestly Fallout had more going for it story wise, compared to Metro, where you had up to 3 different types of foes to go against, and a story that was rather self contained. I liked Metro/LL's stories, but compared to Fallout, they are quite small in lore/tales to tell.
"Six days have passed, on the seventh, I will render myself to a day of rest and to contemplate...what is to be"