def go 4.88 over 4.56s. I paid roughly 1500 for gears, full install kits, a new front carrier, and labor. Do NOT cheap out on the labor, this isn't something you take to "joe bob" down at the corner gas station to do, the installers must know what their doing and do it well. If you get a ****ty install you will have issues with worn out bearings, broken gear teeth, noise, vibrations, ect ect ect.
For the 8.25 I think it costed my 10 bucks more for the 4.88 over the 4.56s... hardly a difference in price. I went with Yukon gears front and rear, technically they sent me USA Standard for the front dana 30 but USA is a "brother" company to Yukon so its basically the same. Go with high quality install kits as well something like Timken or Koyo would be your top choices.