hello. It is all kinda subjective and more of opinion than fact. Any of the rifles will reach 500 yards in low wind. However, IMHO the factory 22-250 and 204 rugers are a little weak for 500 yard shots. The only reason I didn't mention the 223 is the fact you can often find them in a 9 twist that will handle the 70 grain bullet giving you a slight advantage at the longer ranges over the 22-250. If you can find one, I think a 6mmbr is the perfect answer to what your asking for. Easy on barrels, fine for close range deer, excellent accuracy... but not many offer it in factory and it is hard to get factory ammo for it.
I do think that of the three choices you gave... the 22-250 is the last one to get in a factory rifle (I even have one and love it, but I know it's limitations.) If you would have said 400 yards, the choice would be limited to the 204 and the 223. If you were building a rifle, I'd say a 22-250 w/ a 8 or 9 twist.
long story short... IMHO if you intend to burn lots of ammo than go w/ the 223. If not, go w/ the 243, and if your ok w/ reloading ammo and can find one go with the 6mmbr!
good luck, Mark.