It is my first time in this forum so if I make any mistakes pls treat me well. My answer for the question is to be defender. W wins the 1st trick in ♥ We have 3 top ♥ 1♥so far 2 possible ♦ and 2♣ = 8 tricks. We get the chance to get the extra trick by endlplaying S. In either ♣ or ♥ there is no possible squeezee anyway as there is just Q♠ our only communication. Our hopes to Endplay S so we need to cache another ♠ and play ♦ to S's Ace. However S can easily defend himself of being enplayed in ♣ simply caching his A♥ and eliminating crucial ♥ exit from our hand. now he can easily play ♣ to pd's J. As propably everybody has noticed that when S is taking ♦ trick and holds himself from taking A or K ♥ but playing ♣ the declarer ducks , takes ♦or♠ , land in the dummy, plays ♣ S must put Q10 ♣ , declarer wins the trick and plays ♥ S is helpless either ♥or♣trick must be given. So my answer is I want to be S, as it is S that wins the whole prize
