Theon and Asha are very strong characters (in Asha's case, her later chapters are more about POV into Stannis' camp). Victarion is amusingly meatheaded, but I think he was a bit overused.
But then, one of the issues with a lot of the POVs in AFFC and especially in ADWD is that Martin needs to make each POV substantive enough to feel like a little story in its own right, despite that there's not necessarily a huge amount actually going on (the exception being Jaime's one chapter in ADWD, but that's essentially just a postscript to his much lengthier participation in AFFC). A lot of the travelogue stuff in some POVs (Sam, Davos, Tyrion) probably comes partly from that. Like, in Sam's POV, all he really does is go from the Wall to Oldtown. Theoretically that could just be 2-3 chapters, rather than 5.