Re: Remington 700s
All the models you mention share the same action, trigger, and barrel profile. The Tac and AAC are 20" the P and V are 26", slight velocity edge to the longer barrels, slight manuverability and weight edge to the 20"s. The first three are 1:12 twist the AAC is 1:10 and threaded, for most people the twist rates are irrelevent, both handle 150-180gr bullets just fine, the fast twist is for low velocity or very heavy/long bullets, threading could be nice, but if you're ponying up for a can a few dollars to have your barrel threaded won't matter. The Police model is parkerized, the others wear matte bluing, this makes the P vastly more corrosion resistant. The P comes in a real stock, the others come in a chinzy plastic stock.
At the end of the day they're all equally likely to be accurate or lemons, except maybe the P if the accuracy garuantee exists. My V shoots sub MOA with most match ammo. Consider though with any of the SPS's you will want a stock upgrade, and if you use it in incliment weather you'll want to have it coated and after you'll have as much in you rifle as buying the P in the first place, but you'll also have the stock and finish you want.
So if you intend to change everything anyway pick the cheapest in the length you want, if you want to leave it box stock, get the P or spend a bit more on a 5R.