Yup, old thread. But since people are now going to be seeing it again, I'll still toss in my two cents. ;-)
If a player is looking for "good Organs, Brass, Pads, Violins, and Pianos" then recommending a model (or not) because of its sequencer or sampling abilities may not be relevant.
The 88 is a weighted action, the 76s are not, so one big factor will be what kind of piano or organ player you are and how much you are willing to compromise the action in favor of one or the other.
Apart from that, I would be surprised if any of the three were clearly best in all 5 categories; and also, people often disagree about which piano, organ, or string sounds is better than which, sometimes due to personal taste, sometimes in part because of someone's style of playing (i.e. a great rock organ sound isn't necessarily a great jazz or gospel organ sound; a good brass patch for funk won't necessarily work for 40s swing, etc.), so people can easily have very different answers for "which model has the best" anything.
So as for which to buy, you have to see what you think of its sounds (from your own perspective, and based on the kind of music you play), see what you think about the feel of the keyboard, check the manuals and look at the button layout to see what the interface is like and how easy or hard it will be for you to do the kinds of things you need to do.