Either the Minecraft model or the traditional model. The DLC model is ridiculously expensive (prices are high to start with, they almost never come down, and there's lots of small DLC) and it doesn't provide as good experiences as the traditional model does. Episodic content could bring us good experiences, better than what DLC usually is, but it's rare to get episodic content. Also, it wouldn't really have any benefits over having the full game all at once aside from having a shorter release cycle. And of course it would probably be more expensive, too.
Personally I wouldn't mind the DLC model either if DLC was more often worthwhile and a decent-sized experienced but often it is not. One thing I'd find interesting is having a mix of user-generated content and DLC. User-generated content would make game worlds more alive in a way and they would also serve to set the bar higher for DLC, increasing overall quality of games. It wouldn't even have to be all that complicated to add value.
I'm editing this as I go but the sequel model has its flaws too. I don't want yearly sequels, they make me tired of a franchise so quicky. I used to love Assassin's Creed, now I don't even care about it almost at all. Two to three years between installments is a good pace.
