Haven't posted this response in a while.
...Why?
Typically, "best of" threads are posted so that the OP can look up powerful tricks from other people and copy them into their repertoire with minimum effort or research, as a shortcut. Ultimately, this is counter productive, as will be explained below.
However, if you really want an answer, I'll give you a trick, but you'll have to do some research yourself if you want to find it. It's called Artificial Intelligence.
But here's an idea. Look for them yourself, find the ones that work for yourself, and make them "hard hitting"! In all honestly, looking for the shortcut by asking for "best of" effects isn't gonna do you any favours, and 95% of the time will not get you the most hard-hitting effects you can perform. That's right, asking for good tricks will actually, the majority of the time, get you tricks that, when performed by you, will be second rate and common. So you'll be performing the same old stuff and probably not as well as you could be.
Rather than ask "Where can I find the best effect", ask "Where can I find effects (possibly of x plot or from x magician)", go out, look through everything, and find what works for you. You want average material, ask for "the best" effects. And if you're satisfied with decent, go ahead. Some people are happy with being decent, and that's fine. But if you want to be better than that, with the best material and the highest possible impact? You'll have to work harder than that.
The main reason for this is that the strongest effect in my arsenal, in all honestly, would probably not work at all for you. This is due to many reasons - personality, presentation, and just the effect in general. So why would I give that to you? Why would I a) give out something that will probably be inferior for you and b) give out what I've been working on for two years plus? Many, many people for example list Stigmata as their strongest effect, and many people buy it. You wanna know the truth, 95% of people's presentation of Stigmata is ****. Stigmata could be so, so much more. but no, they rely on the effect, rather than relying on themselves as a performer, and this separates the chaff from the wheat. I read a thread just yesterday of a Stigmata performance which was terrible!
If you really want strong effects, you need to tell us what you're interested in, specifically, a plot or an author. Then you need to go look at everything by that author or on that plot, and decide what works for you, use that knowledge to mix the effects together, and base a presentation on what appeals to you, not what appeals to us. My favourite effect happens to be Zamiel's Rose, and yet I barely know anyone who has the personality to pull it off, so I never suggest it, it would be a travesty, the epitome of ruining magic. I mean what do you want me to say - follow your instructions exactly, and give you an effect that won't suit you and you won't be able to make the most of? I'd rather say this, the truth.
See, ultimately, if you're told that in this book, there are three tricks that are good, then you'll (hopefully) buy the book, and go straight for those three tricks. In doing so, you are undermining your own search because you are going by what other people's standards! Instead, if you open a magic book, with absolutely no recommendations, then you are forced to evaluate, for yourself, each and every entry in that book.
This is not to say we (or I) don't want to help. This is to say, rather, that it should be the right help, if you really want the best magic.
Go buy a book or something, that's where the good stuff is.
, I just wanted to see what kind of impromptu tricks worked for other magicians. hopefully I could clear some stuff up 
