Water Country-Portsmouth, NH: The slides are AMAZING! If I had to choose, Dragon's Den, The bowl slide, is my favorite. The food is good too, it's difficult to choose my favorite item, though.
HONORABLE MENTION:
Water Wizz-Wareham, MA:Has a fair amount of slides, some good, some not so great. The food is pretty good as well, the chicken fingers are the best at any water park I've been to.