You in all likelihood have 3.73 gears in that jeep. Might be 3.07 though. Check the diff cover. On the left side there should be a tag. Clean it if you can't read it and it'll tell you what gears you have.
Assuming you have 3.73's and now 33" tires, 4.56 won't quite get you back to the stock ratio and 4.88 will get you "over" the stock ratio. So, either will work and most would select 4.88. (that's what I'd do).
Depends on what you want...slightly better highway MPG and don't ever plan to go bigger tires..4.56
Better (that 4.56) low end and a gear that will allow for 35's...4.88.
Oh, and what diff do you have? Easiest check is: Rubber plug = D35 and metal plug = D44. The dana 35 has been (widely) known to grenade with larger tires, especially while wheeling. Something to consider.