I've not waded through this thread so what I'm saying may be an echo to what others have already shared. That said... the most spellbinding effect going is the one that YOU manage to get the strongest audience reaction from... it's that simple. Fortunately, it will not be the same effect for everyone in that "the trick" isn't what makes the "magician" but vice-versa. Let me give you a couple of examples, starting with the Vanishing Bird Cage of Blackstone fame (both, Sr. & Jr. performed it regularly)
98% of those that present this trick will get a positive reaction from the audience as the result of both, surprise and impossibility. If you executed it properly (which very few do) you may very well have your fellow mage at the club, shocked & amazed (and of course, pumping you for pointers so they can do it as good). BUT, in all of history there are only three major personalities that will forever be linked to this same prop; the Blackstones and Bill McComb.
If you never got to see Billy present this particular trick live, you missed out on one of the most uncanny, enchanting bits of pure magic that ever was. My first encounter with it was from the second row center at the Magic Castle... I was completely awe-struck as he made the cage visibly melt into nothingness in a very slow and quite deliberate manner.
In these two examples we have an effect that has been commercially popular for well over 75 years if not longer and yet, it is only the Father & Son factor that held reign for close to four generations, with the McComb variation being the first to steal their thunder... a bit.
Why?
There must be thousands of those things strewn about the globe and featured in dozens if not hundreds of decent sized stage shows over the past century; so why is it that this single simple effect is only mnemonically tied to three world-classed entertainers?
ANSWER: It's as I said in my opening spiel... IT'S THE PERFORMER THAT TRANSFORMS A TRICK INTO SOMETHING MAGICKLE.
Granted, there are those bits that give you certain advantages, classic effects like the Linking Rings, Asrah, Broom Suspension, or a Guillotine type bit all have "stock" modes of presentation that the majority of us "borrow" simply because THEY WORK. But, it is not until you put your own spin to these bits, that they become "more". Leroy, for an example, had the hardest time getting a reaction from the public when he presented his "Asrah" levitation for the first time (1914 NOT 1902 as some sites suggest) but, when others started working with the piece key elements started coming together and within a few short years, he had a masterpiece... one that still leaves folks dumbfounded when they see a team that knows how to do the effect "right" and using the most deceptive equipment they can find (my personal bias being that Kirby VanBirch has the most impossible little couch and cleanest switch you're likely to run across. He's managed to make things happen fast, smooth and free of the more common drawbacks associated with the effect... but this brings up another point when it comes to the question of "What is the hardest hitting?"
I can promise you, using a John Gaughan "diamond" table Thin-Model Sawing (see Mark Wilson's World Expo-Seattle footage) is far more bewildering than seeing someone working with an Abbott version of the same effect. The point being that craftsmanship as well as prop design & finish can make or break an effect. If you build a pretty glass box on top of a table big enough to hold a small elephant, you're not going to get the gasps of amazement when the girl shows up in it... on the other hand, if you have that same production prop set on a nice clean base, you'll leave them staggered... if you have the pizazz that makes it all come together.
I'm more than aware of the fact that the majority of us can't afford Gaughan, Bill Smith or Owen props and when it comes to the big stuff, most of what we end up with will be used, home-made or possibly purchased from one of those companies that tend to be a bit more "primitive" in their construction techniques. This is however, something that affects us when it comes to smaller stage props, hand props, etc. Even gaffed coins have a quality factor about them that is akin to investing into a Steinway for your home vs buying "a piano" (store brand)... certain gimmicked coins retain that "ring" to them that detours the audience from thinking you are "cheating" somehow... but they are bloody expensive! They are an INVESTMENT and not just a curiosity purchase however.
Ok... another long winded post from Craig, but I hope I've managed to shine a bit of light on this question and the more honest truth when it comes to the answer... but ignoring what I've said, I still have to list the following as my favorite shock inducing effects...
* Card from Magician (mine)
* Asrah
* Impaled
* Buzz Saw
* Spirit Cabinet (mine)
When it comes to Mentalism, my list is very short...
* The Q&A
* Muscle Reading
Laters...