If you ask me, your going to have an ear to ear grin no matter which product you use. The only thing I am HEARING (not seeing) is BlackFire could last a little longer....
I would like to see how many people have used all three product on their silver car. Even if so, how do you know you want your car to shine the same way as his. I would just buy whichever you want and not just use it but try different things, try a massive amount of layers, try to top it with wax, mix waxes, see what you can get from the one product.
I would get Klasse, mainly because I use it and I like it (hey at least I'm honest). There is no "wait" time between coats and it seems like it will last longer than BlackFire. Zaino is nice and all, people swear by it but you need to "wait" (Zaino is removed and it is recommended you wait a day before the next layer). This can be solved with ZFX but you need to consider the cost of that every time you want to use it. If you have a garage and some money, maybe you would want to go with Zaino.
See what I'm saying here...... doesn't matter what you get, your going to win either way.