In reply to GoneFishing111:
The general differences between ascenders are size, shape, and security:
Basic and shunt (and the handle ascender) are quite big, making them easier to handle but heavier and more cumbersome to carry.
The shape of the micro-traxion is a pulley making it particularly useful for a hauling system (e.g. crevasse rescue), the others are all linear ascenders meaning the rope should be straight.
The shunt can slide down the rope as well as up, and so is more flexible but less secure (there has been an occasional accident because it slides down the rope if the device itself is grabbed during a fall). Some of the others also can theoretically fail if loaded upside down.
I use a micro-traxion in my crevasse rescue kit with prussiks and tend to carry it on mountain trad routes in case i want to ascend a rope (using the micro-traxion on the belay loop and a prussik for the leg loop).
I've not done it for a while, but when top-rope-soloing I usually use a shunt as my main ascender and back the system up with a handle ascender on a loose cows-tail on a second rope from the anchor.
I've also used a handle ascender on routes with fixed ropes on big mountains because it is easy to hold in big gloves, and easy to unclip and clip from one rope to the next.
The others I think are used quite a lot in caving and probably aid climbing, and I've not used them. I've found a combination of the micro-traxion and prussiks to be the most versatile and lightweight for most of my purposes.
When it comes to ascending a rope, you can use a combination of any two ascenders or prussiks - one attached to your belay loop and another attached to a foot-loop. I'm sure there are loads of YouTube videos of the best ways of doing this.
P.S. worth noting that there are other brands of ascenders other than Petzl!