* Hoch! This is a good option if you're expressing excitement or cheering at a celebration. It literally means "high!" and is often shouted.
* Hurra! Interestingly, "Hurra" is used in German, borrowed directly from the English word. It's perfectly understandable.
* Hip, hip, hurra! This is also used, again a direct borrowing from English, and is a more emphatic version.
* Juhu! This is a more informal and playful exclamation of joy.
So, the best choice depends on the situation. For a formal setting, "Hurra!" might be best. For an informal, celebratory setting, "Juhu!" or even "Hoch!" might be more appropriate.