This is my opinion, so take it for what it's worth, but I think
the barrels and actions of the Remington 700 are just as good as they have ever been.
The synthetic stocks on the cheaper models is the biggest slip in quality. This has been more evident in the rifles made post-Freedom Group buyout, which was in 2007. IMO the stock fitment issues only apply to the SPS and ADL line of rifles.
Also, I am not a fan of the X-Mark Pro trigger, which came out in 2006. They also went to a matte finish on their cheaper rifles in recent years, as opposed to the glossy blued finish that used to be standard fare. I prefer the glossy finish, but YMMV.
So there are a few reasons one might want to look pre-2006. Another notable mention is the design of the safety. In 1982 IIRC, the safety was redesigned so that the bolt could be cycled with the safety in the "safe" position. So all 700's made before that redesign must have the safety in the "fire" position to cycle the bolt. This is a non-issue IMO if you know how to handle a gun safely, but it could be something you might prefer.
In my opinion, the "creme de la creme" of Remington 700's is the early BDL models from their introduction in 1962 until around the late 70's. The checkering design on the beautiful walnut stocks, and overall fit and finish just seems a little better to me. The checkering design was changed around 1973 I think, the older stocks were impressed, and the newer ones cut. There are fans of each style. You have to watch out with models this old however, (really with any used rifle) because the round count could be way up there, causing throat erosion in the chamber especially with overbore cartridges. But the majority of these rifles left in the factory configuration are hunting rifles that have only been shot a few rounds a year, and are most likely fine.
The 700 is a great rifle, find one you like and go for it.
I have sadly committed the blasphemy of turning this 1971 model BDL in .243...
Into this .308-