There are a good number of choices. What I look for is something that
- establishes credibility (a strong effect)
- catches the audiences attention (no "pick a card" tricks, no intricate manipulation, etc./is flashy, uses flash paper, loud noise, bright objects [usually balloons])
- is visual (penetrations with no/minimal cover, vanishes with no/minimal cover, appearences with no/minimal cover)
- does not use borrowed objects from the spectator (don't borrow personal items like cell phones, money, rings from strangers to open when you are busking or doing walk around. Always, with very few exceptions, do effects to gain an audiences trust before borrowing a personal object)
Pretty much anything that fits that criteria:
- The balloon pop from Jump
The list goes on and on.