BOTH MACHINES ARE BEST.
The GC2310, in my humble opinion, has a better 3pt set up. But that is a fairly minor difference. Both are excellent machines. (by the way, I don't own either).
But, what you may want to do it base your choice on a few issues that will mean something to you.
1) Which dealer treats you better? (this is subjective, but you should feel comfortable with the dealer as he will support you for many years to come)
2) Which tractor is less expensive (given that they are essentially equal machines, the lower priced machine should be given some extra consideration).
3) Which tractor is more comfortable to you? (does the seat adjust enough, do the controls fall in a familiar spot, are they easy to reach, etc)
I could go on and say what my choice would be, or that I like brand X, but really it is up to you and which one you like better based on some of the above questions.