Jack is correct about any oil today being better than what was used in 1917. That means you have many choices. Those choices come with a range of prices. Since all of them are adequate, go for cheap, cheap, cheap. You can buy the chain store's low priced house brand, or you can help the major brands pay for their expensive advertising. My dad was a stillman for forty years and worked at Shell, Pathfinder, and Union Oil refineries. He used to say, "It all comes out of the same pipe." He was speaking metaphorically, not literally, to make the point that all brands are pretty much the same stuff.
The one exception I make for a Model T is to avoid oils that contains metals, which I see as a potential problem for the oil-bathed magneto. Fortunately for me, those are among the more costly brands unlikely to find their way into my T.