I own both. The reason being I like .264 cartridges and neither is capable of doing what the other can. I have a 99 Savage in .260 and could not get a 6.5 Swede to feed no matter where you located the bullet. Then again, I am partial to 160 grain bullets, and can't load them in my .260. Its a trade off. I suppose I lean toward the 6.5x55, but mostly because I have it on a bolt action (Arisaka).