Personally, I think the entire cast of Firefly/Serenity is under appreciated. Nathan has the biggest potential, but as this comment displays, Alan is probably the most versatile, and I completely agree with the sentiment. I haven't seen 3:10 to Yuma yet, but it has received some great press and reviews. He is the unsung hero that everyone loves.
I also picked up the collectors edition of Serenity last weekend. There are a few extra bonus features and an extra commentary track, but really its supporting the franchise in hope of seeing a Serenity 2. With Joss loosing Wonder Woman, I'm not sure what his next project, but some executive at Universal really needs to get with it and green light a sequel. It would be literally like printing money and they already have a huge following to do the leg work for PR!