Between XOM, CVX and COP, Chevron had the most appeal to me and at the time it was trading below its moving averages. (I also only fill up with Chevron or Shell so I was slightly biased).
Specifically for the US, I was surprised California outputs more crude (liquids) than the Gulf.
On the downstream business side they are focusing on high margin refining of oils, lubricants, and chemicals while selling off non-performing assets. The goal is to have this be a steady stream of income to supplement the upstream business growth.
I plan on making CVX the largest slice of my portfolio and will later add smaller drilling and exploration companies.