Although in practice I would use neither. Given how useful forced movement is, I think every wizard should have either Thunderwave or Beguiling Strands as his first at-will, accept no substitutes. For the second, I'd pick any ranged multitarget spell, like Winged Horde or Stoneblood (on a control build), or Freezing Burst or Arc Lightning (on a blast build). Because why would you target only one creature if you can instead target two or three?
In paragon tier this doesn't really matter any more since most combats will be over before you run out of encounter powers.