I would have to see Genesis is one of my favorites when it comes to the Sega franchise but second would have to go to the Sega Saturn
My favorite game of the Sega would have to be Mortal Kombat II and Battle Arena Toshinden
The only tiny complaint which I have about the Genesis port of "Mortal Kombat 2" is that it doesn't use the correct music for the character select screen. Instead it plays the BGM for the "tomb stage".
The correct BGM for the character select screen is used in the Sega Saturn port and in the PC port of the game. Thank goodness that Youtube has both of those renditions available.
This is how that character select theme supposed to sound: