Lawl at people claiming to have mastered the pass.
And to RK... again... 10 points awarded for another useless post. The OP is not asking for a list of the sleights you can do, he was asking for which sleights are proven to be the most useful, and most likely hoping for an explanation. Is it too much to ask for you to realize that not all posts have to be about how amazing you are and everything you can do?
Back to the OP: It is hard to say which sleight is the most useful. The DL certainly is useful, but the problem with it is that many newer magicians will tend to depend on it too much, use it as a crutch, etc... Many sleights can be turned into mini-effects, therefor can be seen as very useful. However, what you will find it that, you need a decent control, maybe a decent force, a false display, a multiple card turnover, and perhaps a color change. Putting these together to form an infinite number of combinations is what makes an effect possible.
Try to avoid the mindset of, "if I can do this one sleight, I will be gold!" There is a time and place for everything, and sure, some sleights have a limited number of those "times" (IE the clipshift IMO is totally worthless), but studying to understand when and where to use which technique is the only advice that I think is worth following right now.