Both tractors would be more than enough to pull a big Round baler.
The only thing that I want to add to the comments of the others is this; if you do buy a 970 or 1070 for god sakes use only Case oil in the transmission.
Hytran Ultra maybe the best oil of its type on the market.
I bought a very cherry 1370 about 6 years ago and made the mistake of changing oil to a brand that i use in my 930 tractors. (All I was wanting to do was have a local source for oil)
The oil was supposed to be a top grade oil.
In the end the oil eat the glue from every fiber disc in the tractor.
It was a night-mare.
A man on this board Agri-King helped me on another issue with that tractor while I was splitting it to repair the ALL of the fiber discs, so I know first hand the quality of advise that you can get from this site.
My suggestion is to go ahead and make the best deal on a Case that you can find and enjoy one of the best tractors ever made.