I agree with Rik. What you've done leading up to the end is going to be a big factor because you don't want to be redundant or if you have a theme going you don't want to directly break from that theme.
An example:I have a routine of card effects with a mental vibe:
-An impromptu, fully examinable version of Sankey's Resistance is Futile. It's quick, interactive and the climax of it is intriguing.
-Daniel Madison's Bad Influence but with the third selection I actually write down which card I want them to pick, fold it up and have another person hold the paper. I tell the third person I'm going to try to send the card to them etc. For the first two revelations I read off what card I told them to pick and then reveal the card they chose to match it. And for the final revelation I first reveal the card that the person picked and then have the person holding the piece of paper unfold it and read it out loud. It gives the whole effect that much more of a mental feel and adds an in your hands edge to the final climax.
-I will close with Sankey's Shuffle Cut Deal. Because it seems so fair and absolutely impossible.
I'm thinking of switching Shuffle Cut Deal with Bad Influence because Bad Influence takes the most time but I'm still on the fence about it. At any rate you can see each effect is presented with a different mental effect in mind. The first being me forcing them to choose a specific card, the second being the spectators unconsciously choosing the exact card I told them to with the final spectator appearing to have read my mind, picking the exact card that I merely thought of. The final effect being me successfully predicting three cards under completely fair, seemingly impossible conditions. Through the performance I'll drop hints about another effect that I may do but I'm not sure of yet. So at the end if they really seem hungry to see one more thing I'll put the deck away and finish with Stigmata.