Well, having had the experience of taking containers in and out of both ports, I'd rate Tacoma miles above for convenience and ease of access. Seattle was just a nightmare with that Spokane Street/ Marginal Way/ Harbor Island cluster. Terminal 18 was the worst - you'd find yourself sitting and blocking traffic only to have the SPD come along and ask you to move. Might be better now, I don't know.

Friendliest, most efficient terminal in my experience: Sealand-Maersk Tacoma, while it existed.

The thing about the Port of Tacoma is once you cross north of HWY 509 it's pretty much all port traffic, no commuters, tourists, or pedestrians. Port of Seattle is the complete opposite, like running a gauntlet of commuter traffic and potential accidents.

What's convenient about Terminal 46? Hard to believe it's still there. C'mon Hanjin, get a grip and get the hell out of there - Tacoma has room for you too.