re: What lumber to use for patio build

Why the need for 10x10 columns? That sounds like serious overkill for a patio the size you are planning.

Treated lumber is likely your cheapest option because cedar, cypress, redwood, etc. will all cost a premium, especially at the lengths it seems you're talking about.

My issue with treated lumber, especially stuff not dried is how much of it will twist and bow as it dries out.

Without seeing your building plan to see exactly what you are attempting, perhaps you need to rethink your building plan so smaller dimensional lumber can be utilized.