Until now, I only played with the Joy-Cons attached to the Switch (good enough for mobile use), the Joy-Cons connected to the grip and the Joy-Cons unconnected. So far, I prefer the Joy-Cons connected to the grip.
This week I also got a third party charge grip (€13 with shipping, USB-C cable included) with longer and thicker handles... feels much better than the original. And the Joy-Cons get charged that way while playing.