I would suggest rough (resawn) Douglas Fir. Prime & paint prior to
construction, touch up as needed afterwards. Just make sure whoever
provides the timber that it is consist dimension. I recently built a
patio cover & the resawn / rough DF 2x10's ran from 1 7/8 to 2 1/8 &
the width were off by even more. We used the Simpson hanger for rough
lumber but even then some had to be trimmed & some were loose.

What Simpson base did you use? I suggest one that give a substantial
standoff from the concrete; like the EPB66.

Most of the Simpson post bases do not have enough standof (only 1") f
to protect the post from water.

cheers
Bob