Early this year I anticipated some transcon travel on Alaska Airlines' former Virgin America flights, so I requested a status match. I got the match to MVP Gold 75K, Alaska's top tier, about 2 weeks later, too late to be of any benefit on my first transcon of the year, which turned out to be my last of the year.
Fate was smiling on me, however. Shortly after requesting the status match I saw a great trans-Pacific fare on FlyerTalk. About $700 round trip on Qantas netted me 38000 Alaska miles. It was almost a mileage run combined with a great vacation. Incidentally Qantas 747 coach to Sydney was outstanding in every way. I would definitely fly them again.
That one trip earned me almost enough miles to re-qualify for MVP, the lowest elite tier. Four short hops would do it. Alaska's top elites get free cancellation and changes and two free checked bags, just like every Southwest customer. Elite same-day change policy matches Southwest's, and 75K's have top priority for upgrades to first class.
I booked five Alaska flights between LAX and SFO at exactly the same price as Southwest, or in some cases lower. I have flown one of them, on which I was upgraded to first class even after changing flight times less than 24 hours before flying. The legroom in first is impressive, if not entirely useful. Seat recline is nice, as are the couple of bags of snacks and the immediate attention of a flight attendant.
I have flown Southwest twice since that one Alaska flight in F. Both times I had an empty middle seat, which happens on about half my flights in Secret First Class (the rows just aft of window exit). My Southwest flights were to and from OAK, not SFO. SFO delays are much worse than at OAK. The Alaska flight was almost an hour late taking off. First class is nice, and so is earning 1125 miles one way, but departing promptly and arriving on time is nicer.
The other crucial difference is frequency. I don't want to enter the quality vs. frequency debate

except to say that it's great to have multiple options when your ride is having irregular operations. Southwest can often put me on a delayed earlier flight leaving at or before the scheduled time of my booked but delayed flight. Alaska's intra-California schedule is thinner. You can pick the time the night before but then you had better stick with that flight. Other options are more spread out in time than on Southwest. If Alaska flew between LAX and OAK and I had MVP Gold or higher status, I would probably still choose Southwest to minimize average travel time.
Alaska has made the choice even easier with its recent announcement of Basic Economy, which they call Saver Fare. By early 2019, all Alaska's lowest fares are expected to become Saver Fares. These are not changeable or upgradable regardless of elite status, making them completely uncompetitive with similar fares on Southwest. I hope Alaska decides not to implement their Basic Economy strategy as currently announced.