[john70t]

Just remember that new posts will probably want to sink a bit at first, and pull attached structure such as the house with it.

Boxed steel is much stronger.
U-Channel is open and tends to dig itself into the ground. Be warned.
You could weld brace tabs on later I suppose. Cut them fashionable.

Any vertical posts should sit on top of concrete-filled sono-tubes 4' below ground at the very least in frost/cold zones.
Something solid. Foundation is everything.
There will still be some minor shifting though.