What is the best up to now high end all-mountain full suspension design? By "best" I mean a design that balances pedaling efficiency, strength/durability, and (lateral) stiffness and weight as best as possible. What should I look for when trying to get such a bike?
Not only is the answer subjective - the "Best" will be different for each rider based on things such as budget, rider weight and fitness and skills, riders tolerance for bumps, riding style (speed, need for control etc), riding terrain, location, brand whoring, day of week, and possibly religion.
However based on you questions criteria, If you must have an answer, I have to go with @GordonM
Edit : ........ Note: This question addresses the original post, which has subsequently been edited.
Legs & Hands
These are by far the BEST suspension you can have in any ride.
- Legs: Fix yourself on the bikes, make a firm grip or the pedals (or use SPD :P), slightly bend it
- Hands: Good grip with elbows pointing out and good balance
Thats it!!! Best suspension is now with you, the one which you can fully customize and control.
I am not saying suspension is not needed.
Having ridden no-suspension, front-suspension and full-suspension bikes I can definitely say that suspension is definitely a very effective addition to your bike, but there cannot ever be a best suspension on any ride I think.
A good suspension with good technology will perform better, but if you know how to use it properly.
Imagine yourself dodging a pit sideways, if you use your suspension correctly it will give you good height, but slightly over and under use and your front wheel will skid on the lift or on the land.
My suggestion would be don't buy a full suspension at first (it will give far too much comfort with no skill). A good bike with lockable front suspension should be good enough to start. Learn to use you legs on bumps, and pits, then try locking your front suspension and learn to use your hands as suspension.
Remember: A smooth sea never made a skillful sailor