Although this appears to have morphed from the OP's question on comparison, sorry, CHOICE between Atlantics & Pacifics, to the decision between Atlantics & Steelies, I have to say that I have been very priviliged to have fished for & caught Atlantics (in Scotland, England, Ireland, Russia & Norway), and fished for & caught Pacifics (limited to BC so far!), I have also fished for & caught Steelies.
As I haven't caught sockeye or chum, my experience is still limited, however.
If I were to make a choice (& I have!), I would go for the salt-fresh Chinook every time. It's the heart-stopping sheer power of these magnificent fish, even in a 12lber!, which not only rip off every available yard of backing off your reel, and test every single ounce of your own energy & skill, and put every component of your tackle to the severest of punishment that will keep me going back for more - not to mention the brutal endurance of a fish that doesn't understand the meaning of giving up. When you hook a 30+lber, oh boy!!!!! , and to think it could just as easily BE a 60lber!!!!
It's the Dean for me, 1st week July (again!!)