At around 1.5MM on United, I left United 1K for Delta Platinum. I commute between SFO and NYC. Of course, United never got in touch to ask what they did wrong. I'm sure they know.

I'm not saying Delta behaves any more honorably than United, but United's generally smug attitude of deceit got to me. I want a fresh romantic partner to break my heart. While selling seats I should have cleared upgrade certificates into at prices I was never offered, United wouldn't even admit a value of $49 for my upgrade certificates. Last year, none of my upgrade certificates ever cleared on this route. After completing a Delta Platinum challenge, I received four regional upgrades that cleared at purchase for future flights, saving me an average of $500 per flight. I'm leaving behind a tree of rotting fruit United certificates, that my friends are attempting to work through. I just want a bar that comps me a few drinks while I pay for biz when it matters. United 1K's ten certificates were a mirage, Confederate currency.

One is being simplistic to read Delta Platinum (75k qualifying miles) as below United 1K (100k qualifying miles). For example, if one flies 50k actual discount business class miles, one ends up with either 75k on Delta or 100k on United.

On this route, the American Express Centurion lounge at SFO has the best food. It is however always crowded, with reserved signs on tables for those with actual status. The one place I know that can make an American Express Platinum card holder feel like a peasant; I'm amused. The Delta lounges at each end are spectacular, not crowded, and the food is good enough and varied enough to end the discussion. I'll take a shower out of boredom, imagining I'm in a Frankfurt lounge. One gets in on an American Express Platinum card, or a Delta Reserve Amex card. I'm switching to the Delta Reserve card, for a multitude of reasons one can figure out if one considers this.

We all know that United lounges resemble Greyhound stations. I've heard they're working on this. Good luck with that.

The 757's are newer inside than United's equipment. There's the different between a touch screen like a cheap GPS (United) and a touch screen like a GPS trying to compete with iPads (Delta). However, there are many 767's on this route. Those are where the least expensive Delta One beds are to be found, and where the upgrade certificates clear at purchase. I've seen empty seats go out in Delta One, before they instituted complimentary upgrades (don't hold your breath). Anyone who managed to fly United's 77W private cabins on this route will salivate imagining these Delta 767 seat maps. Wrong. They're first generation beds, not as bad as United's older 772 beds, but not far off. (They're being replaced.) Barely room to squeeze a briefcase by one's side while sleeping; for security, choose seats with gaps between the seat and the window, the opposite of one's 77W strategy. And the armrest doesn't go down. Nevertheless, I've arrived to one of these seats in desperate need of sleep, and one can when in need. In coach on 767's, avoid aisles on the outside, with underseat space mostly taken up by Soviet-era entertainment boxes (like what the trunk of your car looked like before "class D" amps became a thing). Choose instead aisles from the middle seats.

The Delta One menus promise an experience that would regain Thomas Keller's reputation at Per Se. The food is not better than United's offerings. Worse? Hard to say. Defensive ordering is the dominant term here. I'd rather eat in the Delta lounge and skip eating in the air, like Virgin Atlantic encourages so one can sleep the short hop JFK to LHR.

Delta's boarding is more chaotic than United's, and it's not clear they enforce priority. Still, I always manage to place my bag over my seat when in coach.

Some rules are more stringent on Delta. I moved my last flight a day. That would have been a free change on United; I paid $280 including a change fee on Delta. At least the $80 showed up as qualification dollars; every dollar one expects to count toward status, counts toward status. United is deceitful about this; buying an upgrade is hit-or-miss on counting toward status, and United goes out of its way to not tell you, as we all know. Award travel also locks in sooner on Delta. Making the transition, you're a lawyer moving your practice to a new state. You need to bone up on the new rules.

Delta's international network nonstop out of SFO is more meager, relying on international partners. Effectively, this means one is looking at coach minus. Or figure out booking Premium Economy on the carrier itself, crediting to Delta. United has its own international metal out of SFO. On United I could buy coach and waitlist a GPU (these did used to clear, in the era of gas lights), sitting in Economy Plus for sure.

The above is the primary reason I have an advantage on Delta. Anyone with broader needs, on someone else's dime, is instead on United.

I'm looking ahead to a couple years of part-year travel, as I take an academic sabbatical. It will be far easier to maintain Delta Platinum status, with the Delta Reserve card, rollover qualifying miles, and such. I'm leaving out the details; study them before deciding.

Last year I spent nearly $15,000 on United, with a bed 77% of the time. This year I'm spending nearly $11,000 on Delta, with a bed 53% of the time. That's good enough; I can think of other uses for the money.