There is no "better". Two joint states serve completely different functions.
Hold is needed to preserve the shape of your limbs and body so they won't give under stress. This is useful for blocking, balancing, and dishing damage. Relaxed joints are used when you want certain limbs to naturally bend under gravity or use a flailing strike. They also come in handy when you are trying to land from a high altitude, because relaxed body will absorb stress from the landing more evenly, you just got to make sure you don't dq.
I like to think of held joints as tightly inflated soccer balls which don't give in and thus channel energy very well; exactly opposite of relaxed joints.
PS: the whole "more relaxed means more pro" thing is 100% not true. While most new players start off very stiff, it is simply due to the fact that they can't balance too well and thus don't risk relaxing too much.
Last edited by Odlov; Oct 25, 2009 at 10:24 PM.