It depends on how they are funded, of course. It's not parks (or any other form of public property) that "takes away our freedom", it is the fact that at this point in history they are created and maintained mostly via coercive taxation.
Now, for the foreseeable future, I would advocate expansion of the system of American national parks and of conservation in general.
While we are trying to make coercive taxation less barbaric, and eventually eliminate it, money that is collected currently could be spent in many different ways. Right now, a good deal of it goes to government activities that are dubious in nature, or outright harmful - from the Idiotic War on (some) Drugs to market-distorting corporate welfare. Conservation of land and ecosystems (without violating anyone's property rights) is undeniably a positive thing, in itself.
Publicly held factories or schools suffer from numerous problems that boil down to (1) the dilution of personal interest and responsibility, and (2) the accumulation of errors in the absence of market feedback. But the basic job of preservation (not allowing interlopers) is a police job appropriate for government agencies. Socialist methods are quite effective, when your goal is to prevent things from happening.