Patellar tendon graft was the gold standard. Hamstring grafts are becoming more the norm. With the patellar graft there is the problem with an increased chance of arthritis later on and the "phantom itch feeling".
With the increasing popularity of the "double bundle" technique, hamstring grafts can be made as strong as patellar tendon grafts. Similar to patellar grafts there is basically no chance of rejection if you are the donor. The drawback to hamstring grafts is that the hamstring never quite gets to 100% (from personal experience and talking with 3 friends who have had the procedure plus it just makes sense). My left hamstring is also more susceptible to cramps now compared my right hamstring.
Cadaver grafts are great as long as your body doesn't reject it. Happens in <1% of cases. Also if you happen to be super unlucky (think mega lottery/lighting chances) you can die if the donor ligament or tendon was infected. Cadaver grafts have an upside however since it is the easiest surgery and seemingly quickest recovery. I say "seemingly" since you might feel like 100% back after 6-8 months but your cells may have not fully "converted" the graft into their own quite yet (there have been very few biopsies to confirm this however). You are also not limited (relatively) to size of your graft (i.e. you can stick a thick graft in there instead of being restricted to the size of your own ligaments). I waited a about 11 months after my second surgery before I went skiing again. I had a cadaver Achilles tendon put in there.
Studies have shown, however, that the majority of ACL failures are due to poor graft placement, not the type of graft. So find a orthopedic surgeon who specializes in knees and understands sports medicine!
So my point of discussing this was to say that if I could do it over again I would seriously consider having a cadaver graft first because it would not weaken my hamstring (which is a key muscle in preventing ACL tears). I think of it this way, would you want a strong graft taken from a muscle that protects it? Or a a pretty big graft that after time is strong, protected by muscles that have not been altered?
Obviously I am not a doctor and you should listen to yours, but ASK questions when you see him/her. Have them list the pros and cons. Take some initiative into what is happening in to body.
Also become a beast in the gym/on a bike/on a balance board/in yoga class...haha.
As for preventative training. I have been trying to get some traction in this community on that topic. Feel free to bump some of these threads.
New forum section about injuries and training:
Pro skier workouts:
^ I would especially like to see the latter since the Olympic teams were just announced and I know they are going to be doing some serious training. Which might kill the spirits of kids who think you don't need to train to be better at skiing.