what are your best impromptu card tricks

Ambitious card.
A four ace production if you can cull the cards during the previous trick.
I'm hoping Singularity will be one of my best impromptu tricks once I perfect it.

Everytime you ask this type of question, you'll get people answering ACR, and that would probably be my answer also.

Miracle Card (Ortiz)is hard to beat. If I can ever get Bureau de' Exchange (Earick)down it will likely be tops on my list.

Tevo 2.0 (Buck Twins) is great but has angle issues. Good for two or three people. I also like Subway (Buck Twins) but find that spectators might not follow what's going on unless it is a phase in your ACR.

I don't really care for standard ACR plots but if each phase is an effect in its own right they can be lots of fun.

Search and Destroy (Fisher) is a nice effect if you have a mellow, conversational atmosphere.

Truth be told, I think impromptu is overrated. It is nice to know a handful of solid impromptu material for those rare occasions when someone tosses you a deck and says, "show me some magic!" but once you have some solid and convincing false cuts and false shuffles you are holding yourself back not stacking the deck in some way. Whether it is a gimmick you can ring in, Aces prepared for an ace assembly, a partial stack for a gambling demo, or a full Si Stebbins style stack prepared for some amazing card memory tests. All that matters to me is that the spectator thinks it's impromptu.

To be honest, a simple card-to-mouth on its own does the trick (no pun intended) for me. I know to some, it makes no sense just doing it by itself but if you are just asked to do a trick, that one is by far my favourite.