All lakes will produce fish. I've never stayed at any of the resorts your looking at but have passed by Southview on Rice many time from the water and it looks like a nice place. If you chose either Rice or Stoney you'll be close enough to Peterborough that if the kids are bored you can head to town and kill sometime. There's lots to do there, with the zoo(free), movies, canoe museum, and lots of park areas.
Like Lew said the bass fishing doesn't open in the area till last week of June and no pike in the kawarthas but there are muskies to be caught.
Good Luck with your choice.