I had the original Go but didn't like the limitations (can only use go dies, which will never be bigger than 10" for the die itself) so I sold it and got the big shot pro (sizzix). I love the BSP but it is huge, expensive, heavy, and is not portable. But it can cut almost any die on the market. So it depends on your needs. Also, the BSP is much easier for me to crank but some have said they have improved the cranking on the Go.
There's also the accuquilt Studio cutter which can cut every die on the market, I think. It is also huge and expensive though but very versatile and heavy duty.