I've read up on all of the top OL in a class that is clearly quite deep, and two guys in particular stand out to me as not just day-one plug-in quality starters, but also (given health), with great potential to become all-pro types at some point in their careers, even very early on, like by the end of their rookie seasons: Joe Alt and Taliese Fuaga.
There are others too, with perhaps similar upside, but none with corresponding super-high floors and/or well-rounded elite pass/run blocking of these two IMO. And others with decent floors, but not nearly the upside. To me, the only thing I would struggle with in placing Fuaga with the elite of the elite prospects would be if my team needed him to play LT, instead of RT. He hasn't done it on the left (yet), and while his pass pro was very solid in college, he may not be ready to protect the blindside on day 1; or ever even, if he has peaked already in terms of his pass-blocking development. Fortunately for the Raiders, they already have a stud LT, who is still early in the prime of his career.
Was it worth trading up three spots and sacrificing a 3rd rounder (getting back a 6th) to do it? Firstly, this guy is an absolute BEAST in terms of run-blocking and physicality - the clear and distant #1 of this OT class in terms of those two aspects. He is not only mean and nasty on the field, but is also a confident alpha leader personality. He is exactly the type of guy Harbaugh and Saleh, and most importantly, Pierce, covet as cornerstone, tone-setting players within the heart of their teams along the OL/DL. As I look at 3rd round vs. 6th round players in this draft, I'd gladly give up that delta in order to make sure the Raiders get Fuaga and perhaps almost as importantly, the Chargers do not.