Defiantly Google.
A few reasons actually:
1. Bing has many ads popping up at you, and disturb your typing on the search bar.
2. Google has nice animations(sometimes) and celebrates birthdays of people around the world. Also popular holidays.
3. It has COOL tricks. {EX: Zerg Rush, Google Gravity, Barrel Roll}
4. If you type in something (Say, Hawaii), it will give you WAY more relates than Bing ever will.
On a somewhat related topic:
Yahoo is okay If you like using Yahoo Answers, like me, but I still prefer Google.
Poll