Cesiumsponge
This is my opinion, but I would say bolt-actions are the simplest and most repeatable firearm platforms, hence giving the most consistency and repeatability which is crucial for achieving the smallest groups. Semi-autos have a lot more moving parts that will not repeat as well round-to-round. They get dirty faster, and are more picky because they need to cycle rounds to function properly. I plan on aquiring a Sako TRG series or the AW series from AI eventually.
That said, semi-automatic firearms have advanced a lot and they're quickly gaining ground in reliability and shrinking their group sizes. The AR rifles appear to be leading the pack on accurized semi-automatics. The M1A's have a loyal following as well.
Personally, I feel the PSG-1 is a fairly old rifle. And there is very little information on it, so its difficult to tell if it lives up to the mystique it has created. I've only handled one briefly so I can't speak to it's actual performance. The same applies to other rare firearms like the Walther WA2000. Rare doesn't mean top performing. If that were so, it's very probable world class competitors would be using these, despite their premium price because accuracy is final and price is secondary when they have gobs of money from their own pockets and sponsors.
I've read good things on the AR-10 from Armalite and the DPMS LR-308. Many people are getting 3/4MOA, even around the .5MOA mark. I have a DPMS LR-308 on order right now and it's going to be a long (but worthwhile) wait. I have heard that the SR-25s are overpriced by about a factor of 2-3x and you can build something similar at less than half the cost from DPMS or Armalite. I briefly handled one at a local show and it was impressive, but didn't seem special enough for the sticker price. You just don't get their cool crest logo and bragging rights of having an actual SR-25.
I suppose its the same animosity felt towards other AR15 rifle "clones" by Colt fans.