I presume you're talking about the outboard bearings that work the hollowtech crankset.
Any Shimano road bottom bracket (7900, 7800, 6700, 6600, etc.) will work for your 7800 cranks. Other manufacturers units, such as FSA) will work too, but be watchful of bearing width. You may need shims. If you stay with Dura-Ace or Ultegra, though, you can't go wrong.
I'm very satisfied with 7800, 7900 should be at least as good, and the only drawback to Ultegra is a few more grams. Also, your local shop may be able to simply replace the bearings in your existing cups.