I've always thought (and still think) that Roth was great as Blonsky. Laid back, reserved, not too over the top, but still someone you could see was always on the breaking point of going over the edge. I'd love to see him back as the character, Roth in general is a very talented actor.
As for Ruffalo & the Hulk in AoU, I can't wait to see what's brought to the table. It'll be refreshing to finally see the same Hulk brought back from the previous film. Not gonna lie, I was getting a little tired of the design change from film to film. As much as I loved the design in TIH, TA nailed it perfectly. But, that's the benefit of working with ILM.