These cards were low and stagnant for years. I last collected T206 in 2005 and until 2015 I still pretty much knew the prices. They've gone up a ways but I think most of that really just made up for lack of consistent growth. I believe that some of the cards are still undervalued.
Beyond T206, i don't see how you go wrong with Ruth, Cobb, Young, WaJo, Matty, Gehrig and a few others from the great prewar sets. There are still good ones to be had at relatively low prices.
As for why a T206 portrait, well, look at them. They are beautiful little lithos. Even in lower grades
