Why did "franchise" ever spread out of business talk? Can't we, normal people, use the normal word, "series"?
Anyway, I'm a happy video-game consumer today, very excited to see that Baldur's Gate™ is still recognized as the best BioWare Corp.™ interactive experience franchise even if its production values can't compare to today's products.
As good as BG series is I gave my vote to NWN series due to the modding scene. You get the most bang for your buck out of the mods and persistent worlds. I hope another CRPG with modding potential like this comes out soon.
Mass Effect here. I'm an old timer, played through all oldschool sagas, and none of them had me so impacted, feeling like I had real loss when a character died for good as part of the story as Mass Effect did.
Baldur's Gate had good storytelling, but it's eons away from Mass Effect in its ability to really make the player feel as if she was the protagonist.