"Best" will depend on many circumstances...like what you want the character to be, what pose he is in, and how much room you have for storage! Start with a solid wood base, and work up from there. I am currently making a groundskeeper for my cemetery using scrap 2x3s and a scrap piece of plywood so far. Plastic shopping bags for a little stuffing, etc.
His right arm will be out holding a lantern, so I'll probably use PVC to contruct the arms and make them hold a pose without being "squared" like lumber would be. When he'd done I can drill holes in the platform and stake him to the ground so he doesn't fall over!
Any time I've made a character, I just use whatever I have laying around that's not already in use, and work from there.
Old boards, pipes, wire, branches...some burlap or torn jeans or old shirts or coats...rags or plastic supermarket bags for stuffing - or packing peanuts in plastic bags (yeah, I've kept them for just such a reason)...
Basically, anything to get the basic shape, form, and pose - I'll add details as I go along.
Yeah, it really depends on the TYPE of static character you are building. The first thing that came to my mind is monsters with PVC, Chicken Wire and Monster Mud, but that wouldnt work if you just wanted to build a human form where you just needed something like PVC, Pool Noodles and old clothes.
When I made my figures in the past, I started with a 2x4 frame. For standing figures, the boards were cemented into boots to support. Then the upper half would be PVC secured to the 2x4s, ie neck,arms,shoulder. The filler would be foam stapled to the wood and wrapped and taped around the PVC with duck tape. To support these standing in wind, you can have a board set in the ground at the back of the figure.