Thanks for all the inputs!
NLBwell's comment made me doing the recap. I realized that without sound footwork, there is no good timing, and no solid stroke consequently. Racquet plays an important role, but so do footwork and timing.
Now about the racquet, a friend of mine has both Head Prestige 300 MidPlus and a Yonex Vcore 98D. I tried both (both have Luxilon strings), and I think they are very capable racquets with different feel. The Yonex has crisp-feeling, and can be a bit hard on the arm.
The Prestige 300 has the distinctive Prestige's feeling.
So, I've decided not to get neither the vcore 100s nor the prestige S..