If we are talking about sheer variety and not how strong the IP's are sales wise, then Sega as a whole has probably the most diversity in unique characters and IP's out there.
That's what made them so unique. Few big publishers would touch something like Ecco, Nights or Jet Set Radio and certainly not invest too heavily in them, yet it was the kind of games Sega tried to sell their system's on. I think you'd be laughed out of the boardroom at Activision Blizzard for suggesting titles like that as some company's most important games.
"A dolphin? No, no, no, games need more shooting and grinding.."