My favorite franchise would have to be Fallout. I love how deep and rich the story is. There is so much detail. When I finally completed it I had clocked in almost 170 hours. It was that good. Second would have to be Assassin's Creed. Followed closely by the entire Zelda series
My all time franchise choice would have to be Call of Duty, due to the intensity of the military style base of the game, plus with the addition of the Zombie mini mode in World at War and continuing it through Black OPS.
Secondly the Fable series, it offers a lot of room to grow your character and gives a good storyline.
Thirdly Fallout. As it is one of the best futuristic games on the market.
Call Of Duty. I have followed Call of Duty ever since the originals for original xbox.. And they just get better as they go on. There is truly nothing like them and all the rest out there. And all the extra little bonus perks like Zombies on black ops just makes the COD franchise 10x better.