Kidcoltoutlaw,
I have shot the Sako in both .308 and .338LM, have only shot McM's in .308 and .300WM. Hands down, I would go with the Sako. In my experience (comparing .308 to .308), the stock was more ergonomic, the rifle is lighter to lug around, and accuracy was just as good, if not better than Mcmillan. You can easily purchase a Sako from a distributor, and will have to wait if you go the McM route. Now that production tactical (or sniper, or long range, whatever phrase you fancy) rigs are cheaper and perform similarly, or better than custom rigs, I see no reason to go the custom route, unless you really want something customized - i.e. particular action type, certain stock, etc. Both the Sako and the AI AE guns are exemplary - if you must have a Mcmillian stock on your gun, the top level FN bolt guns are the ticket. You will probably get a better return on investment going out-of-the-box. Custom guns usually don't fetch near as much as what you paid for them because if someone wants a cutom gun, then they will pay to have it customized exactly the way they want it, rather than settle for yours. The only customs that I have seen retain most of their value are the Chandler Snipers from IBA. They don't build many of them, and they are the most hardened Rem 700 action bolt gun out there. In this gun, you are paying for the robustness and for the Chandler name. Unfortunately, GA, TBA, McM, and the other custom guys out there don't have the same amount of cache as the Chandlers, even though they are building fantastic guns. :-( The upside to that is that you will build you a similar quality gun for less, and resale doesn't matter if you are going to use it forever.
Good luck with whatever you decide! YMMV
SCL