RE: Rem. 700 or Browning A-Bolt
I have several of both.
Most all of my Remingtons either are or soon will be customized. The Abolts I own are mostly stock/ as they came from the factory. You can't beat a remington if you intend to spend money on customization. There are more aftermarket parts for remington 700's than any other. Also, all Benchrest actions are basically clones of the 700. they are milled to tighter specs obviously. The 700 has tremendous accuracy potential. The problem I see with factory rifles is that the barrels are quite rough. they foul like crazy and accuracy is inconsistant.
If you plan to leave the rifle as is I would probably lean towards the Browning