They both have an equal amount of upper body work. Either will give you a great upper body workout. And I agree with julier, you'll regret not getting both. I, too could afford only one, or so I thought, and got the Millenium 2, and LOVED it so much the first time I did it, I immediately "found" the funds to order Millenium 1! I could have saved myself the double shipping cost if I had just gotten both!
Donna