For me they both have a certain charm. The OT Yoda has a more grounded & nostalgic feel - the PT Yoda is obviously more active & expressive. I think by the time they hit RoTS ILM really nailed it.
I'm hoping when it's all said & done all the Yoda's in the PT are consistent and in the OT if anything is done it's something along the lines of what AdY is currently doing (subtle tweaking).