Everyone is going to have (1) different ear canal shape and response, and (2) different taste. No problem! Enjoy what you find to be the best for you, of course. That's what we should all do. No product will satisfy all.
You mention most people like large ear tips because they get a better seal. Well, for some ear canal shapes (and they can be widely different), smaller tips will seal better because they can be pushed in further for a better seal. Apple provides three sizes of cover for this. Etymotic, on the other hand, provides a rubber seal that has a cone shape so it can be pushed in until the taper seals. They also provide a different kind of foam seal that you compress, and then within several seconds it expands and shapes itself to the ear. These are spectacular. They provide maximum isolation because the foam is very sound-insulating, and they also shape exactly to the shape of the canal. These foam seals are extremely comfortable. You have to change them often, though, because after several uses, they don't compress as well.
Also, the Apple earphones are designed to be flat (that is, reproduce what was recorded), while some other earphones are designed to accent base. There's not really a right or wrong (although audiophiles will tell you that a flat response is best because you're hearing what the recording engineers expected you to hear).
More base is good for some songs, but not necessarily for others, and if the boost is artificial -- like boosting the base on an equalizer for a high-end room stereo -- then it might sound better but it is not truer.
Now if earphones cannot reproduce the base at all or are muting it substantially (and I know that is what some are claiming is going on with the Apple in-ears), that's of course a big problem. But there is a difference between not reproducing and artificially boosting.
And I think, for some, it is a matter of not getting a good seal. Without a good seal, the Apple in-ears can't provide the sound they were designed for.