Cream eyeshadow is really good underneath a pressed or loose eyeshadow. It's great because it makes the colors even more pigmented. The only problem with cream is that unless it's specifically creaseless (the MAC paint pot would be an example of a creaseless version), it can crease really badly. So I wouldn't recommend putting it on or above your crease; just stick to the lid. If you have oily lids, I wouldn't recommend doing a cream eyeshadow at all, because it will just slide all over your lids throughout the day.
Loose eyeshadow is my least favorite of the three. I actually don't use loose eyeshadow at all except for MAC pigment; those are the only ones that I make an exception for. Other than that, I honestly don't even buy loose eyeshadow. I just think that they are kind of messy and there's nothing you can really get from a loose eyeshadow that you couldn't just get from a pressed eyeshadow. Also, loose powder can make a serious mess on your counters!
Pressed eyeshadow is my favorite. My guess is that most of you use this version, too. This is the most standard eyeshadow formula because it's simple, easy to work with, and can be used for a whole bunch of stuff. You can use pressed eyeshadow as color on your lids or liner on your eyes. You can even apply it with water or layer it with other eyeshadow formulas for different effects. It's basically just super versatile and to the point. There's not a lot a lot that it's NOT good for.
What formula do you prefer or use the most?