Pellets are available in plain and scented varieties. Glass beads are easy to use. Glass beads are recommended over steel shot due to health reasons. Since they are washable, they are excellent for teddy bears made for small children. You can't make fine adjustments on joints with a flange system.
Screw joints are easy to install and can be fine-tuned.
The disks are connected by the cotter pin, whose ends are bent like a snap or a crown with needlenose pliers, to secure them. It takes some practice to learn to do this. You can flatten the loop of the cotter pin to a T or thread a small washer to the loop to keep from pulling it through the washer. Of course you will be limited somewhat by the dimensions of the upper portion of your bear limbs. Otherwise you can really decide yourself.