I'm not sure what type of boat to recommend, but you have the spectrum of river-running playboat to full-on playboat.
You may want a playful river-runner that has a little length to get through some Class 4, which you're looking in the sever foot range, or slightly longer. These boats can spin, even cartwheel, wave wheel, but have more speed to punch through downriver challenges. There are several of these boats out now. A decent used one for cheap that I like is the Wave Sport EZ (Or Big-EZ depending on your size), if you can find one. A modern one with better outfitting that has been getting great reviews is the Jackson Fun series. There are a couple other seven-foot'ish river-running play boats you might want to check out too.
If you are looking for a full-on modern playboat, I'd highly recommend a Star, All-Star, or SuperStar (again depending on your size) by Jackson Kayak. I've found this to be about the easiest modern playboat to paddle. You can even find one used a few years old that will be great. There are a dozen or so other models of this type of boat worth checking out, both new and used. This type of boat should be great at the whitewater parks, but you may or may not feel limited to class 3 because these six-foot boats have a downriver handicap compared to boats a foot or two longer.
Just FYI the biggest brands in new playful boats that you're probably looking for include Jackson, Wave Sport, Dagger, Pyranha, Fluid, Liquidlogic.. You can check out their boats online.
Good luck in your search!
Two things you might be willing to share:
-how much do you want to spend?
-height and size?