I love both, but as most people know, BoFIII is my favorite entry in the franchise. The story better balances warmheartedness and dark moments while having an overall more tightly designed gameplay. Fou-Lu is the best part of IV but Ryu's section just gets too bogged down by meaningless and transparent mini-game distractions, and the new game mechanics either don't mesh well with what they brought back from III or they changed it in a way that feels a bit too backtracking like the Dragon mechanics.