Like in a previous blog James Spader was the only pick for Ultron it's being confirmed now through quotes by the man... uh... robot himself James Spader:
"I have spoken to Joss Whedon about it," Spader said. "Just this weekend I went in for them to take very extensive photographs, head scans, body scans, and all kinds of things in preparation for figuring out how the hell I'm gonna fit in this Ultron character!"
"I'm not a planner," Spader added. "I like to try something different, to just see what happens... I think it'll be a lot of fun and it's incredibly nostalgic for me. When I was a kid my best friend had trunks of comics and I didn't have any so I used to love going for sleepovers at his house. Also I have three sons and two of them have a great interest in comics so they're excited I'm playing the role."
Having this much preparation is going to prove that the time and effort going into this sequel and villain and choice is going to be better than we all think, I'm still on the fence but that's another discussion for another media option.