Your skin type and the coverage effect you're going for is crucial to any decision about foundation.
Some people with oily skin prefer Studio Fix powder compact foundation for a satin/matte texture. I'm not a fan since I find it kind of chalky, but lots of people adore this.
Hyper-real is liquid with this pearly effect that catches the light and adds a dewey look. Again, I don't like this because it looks to me like the person wearing it has been sweating for days.
Studio Tech is a creamy compact foundation that offers a surprisingly natural finish if applied sheerly. The downside to this is that it can break people out like crazy, depending on their skin type.
Select Tint is a liquid foundation with ultra-light/sheer finish. Very subtle, but doesn't cover a lot.
Select SPF 15 is a good solid foundation for medium coverage. Nothing incredible, but not bad.
Face & Body is kind of like a tinted moisturizer. This can be quite greasy-looking, though and has been known to break people out.
Full Coverage Foundation is a very thick, creamy compact foundation that is best for photo shoots. This will cover anything, but is very cakey and obvious. Also not good for skin that breaks out.
Moistureblend Compact Foundation is a creamy foundation for dry skin. I've never tried this, but the reviews I've seen have been disappointing. Very emolient and greasy, also causes breakouts.
Matte Foundation is liquid that dries to a very matte, heavy finish. Ick.
Satin Foundation is not the best coverage, but is quite lightweight and straightforward. Good for subtlety with a bit of coverage.
********************
Basically your best bet is to get yourself to a counter/store and try the different types out to see what works for you. Try to get a sample if you can and give it a shot for a week to see the effect it has on your skin.
Check MAC's website for prices.