I like the screw piles. They come in different sizes, and around here, they are the same cost per pile. If you beams can handle the span, you can use fewer piles(assuming locals codes allow).
They guys who installed mine was a 1 man crew, and done in 1 hour and they were all exactly where I marked them. I can only imagine how long it would have taken to dig all the holes mix concrete. The soil here is mostly clay with some rocks, if you have really rocky ground it can kick the pile off crooked or jam them up so they can't provide the proper support.
PS The only part of the my deck currently near/touching the ground is the stairs, and frost tried to lift the deck by the stairs. The posts and beams didn't move, but I think I may try and float the stairs instead of having them rest on the ground. I need to figure out a way to skirt the deck without having the frost try and lift the deck by the skirting.