Go and accuquilt studio dies can be used on the sizzlx big shot pro but sizzlx dies cannot be used on the go. Sizzlx dies tend to be cheaper than go dies. There isn't an electric version of the sizzix, at least as far as I know, so if you want to go that way it'll have to be the go big.
I love my sizzix but you want to consider whether there are dies that you will use often enough to warrant the cost. Look into both and then make your choice.