This is a no brainer, Alaska/Horizon is the way to go for you. The cities you mentioned you travel to are mostly served by AS, and the ones that aren't have plenty of partner access. The cool thing about Alaska is they have partners in both OneWorld and Skyteam, the two most notable being American and Delta. Tons of great international partners for redeeming those miles for lots of bang for you buck too Qantas, British Airways, Cathay Pacific and LAN all immediately come to mind.

Domestically, Alaska has the highest availability of award space for any US airline except for Southwest. I believe the number is something like 77% of all AS flights are available at any given time for redemption at the lowest level.

AS MVP is also probably the most valuable bottom tier status you could ever have as well, if you get there. When I was an MVP, I almost never missed an upgrade. I had a better upgrade percentage than many top tier elites on airlines like American and United. AS elites also get free upgrades on Delta when space is available after all their elites have been upgraded.

AS has a couple Visa card options, and there's a great AS Visa business card with tons of worthwhile benefits. They even offer a debit card that earns you miles if you want one of those too. Here's all the stuff you get with the various cards:
https://wwwa.applyonlinenow.com/us/a...2157572-299118

I have many other options for my loyalty, but Alaska is without a doubt the best, easiest, most valuable program to be a part of.