i don't want to use lego in particular because first lego is easy to brake second it won't really make want im trying to make.
i think i remember that guys name now... was it lama? that guy who made his own figures?
Actually the ABS used on lego is ridiculously durable. It isn't on par with POM/Celcon, but it's certainly good for what it's meant for.
I know I have a lot of advice posted in some topics, I'll have to hunt them down and post them here. Joint setup, contrary to previous advice, shouldn't just be "let's buy some revoltech joints and pop them in all over!", you need to take the time to figure out what you want and make sure you have sets of durable, more easily placed joints that work for what you're doing. Almost all of my modern stuff requires gluing/heavy modifying of previous pieces to make joints that work. I have a lot of scrap tamashii/bandai of japan figures which have some really nice quality POM plastic, separate (or close to it) joints that work really well. However, I assume your inventory isn't at all like that, so to begin with, you should probably check out HLJ, Hobby Search, or Amiami, because they'll have separate joint packs (just look up joint, you should get several different listings), and pick out what you think works for you. Problem is, none of these use POM -- In fact, the quality on some older ones are horrible, so I'd suggest you make sure you look at only items from 2011+.
Here's a joint setup that can act as a half assed guide.

Now for sculpting, it's really about what medium suits you. The ideal figure will have its parts casted into resin, meaning you could use whatever material you want. However, assuming you're out for something amateur (though you insist legos are too weak, which this'll go against), you can use super sculpey and make sure you bake it properly. Obviously, you cannot bake any plastics with it. On the other hand, you can use Fixit/Apoxie sculpt, Milliput, or Green Stuff, which are all duel compound air dry epoxies, which are more durable, but a lot more difficult to sculpt with.