I like 3rd Party for things like controllers, but since none have been released yet I'd have to say depends.
I have a 3rd party battery charger, and a 3rd party wii gun. A friend of mine actually has the wii sports accessory package, and believe it or not, he has gotten far better because of it. As for me, I don't bother with those accessories only because of money, but if they were given to me for free I would use it for sure.