I have had both and hands down, love the Big Shot Pro. I sold my Go because it was hard to crank and so limited. There was no way I'd ever be able to cut 10" squares on it (the bed is only 10" wide) and could only use Go brand dies. The Big Shot Pro can use almost any die on the market. It is so much easier to crank and I have a nice 10" square die that I bought for it. I love it.
However, it is huge, and doesn't fold up, and is HEAVY. You really need to have a spot where it can sit out all the time. But I love it anyway.