Take a good look at the 3 websites below. You would end up earning top tier status on whichever 1 or 2 airline(s) you choose. But keep in mind the lower tiers, as you will hit those tiers on the way to top tier.
Based on what you typed above:
Mileage Accumulation Rankings:
1. DL (25% bonus after 25K MQM, 100% bonus after 50K MQM, 100% bonus after 75K MQM,
125% bonus after 125K MQM)
-Source:
Delta website
2. AA (25% bonus after 25K EQM, 100% bonus after 50K EQM, 100% bonus after 100K EQM)
-Source:
AA Website
3. UA (25% bonus after 25K PQM, 50% bonus after 50K PQM, 75% bonus after 75K PQM, 100% bonus after 100K PQM)
-Source:
UA Website
Ease of Award Redemption Rankings:
1. UA
2. AA
3. DL (distant 3rd)
By most accounts, UA is best for easy online redemption and excellent availability (even for most partners). AA also is pretty good (with excellent off peak international redemption rates along with discounts on some domestic destinations if you carry their credit card), but they're somewhat handicapped by a more limited array of international offerings and a less stout route network on Oneworld rather than UA's Star Alliance. DL falls very, very far behind in online booking capability AND award availability (for award availability, note that they're very stingy with awards on their own metal; awards on partners are often available, but they're usually difficult or impossible to book online, with few exceptions).
Upgrade Percentage:
1. AA
2. DL
3. UA (distant 3rd)
From my understanding, you'd likely see the most regular upgrades on AA, especially because they only give automatic upgrades to their top tier, Executive Platinum, elites. You reach that tier after only 21ish round trips (or after finding a way for them to match other status you've earned; used to be tricky on AA, but you might find luck if you try to go that route; window has opened recently, especially for UA 1Ks, but it may close by the time itd be relevant for you). Also, you get SWUs when you hit Executive Platinum with AA. They're most valuable for paid international flights, but if you end up really wanting to guarantee a domestic upgrade, you can use them on those too.
DL Diamond status would put you in good shape for DL upgrades. Also, have in mind that on some of your work fares (if in a high fare class), you may also use the more-limited-than-AA upgrade certs that DL gives you when reaching high status levels. Have in mind that when you reach Diamond status, you also get free DL airport lounge access, which might be nice pre-flight. Also, ponying up for the DL Reserve Amex wouldn't hurt, though even without it, you'd be in better shape than with UA.
From what I understand from other posts, UA does not complimentarily upgrade any of its elites on JFK-LAX, and EWR-LAX (if convenient for you, that's another story, but if not...) is apparently tough to come by re: upgrades. So UA seems to lose in the upgrade category on the NYC-LAX route.
Remember that JFK-LAX is, in general, tough to upgrade, but you should be strategic about this, because you might find that with your rigorous travel schedule, upgrades will become more important than you expect.
Conclusion:
I'm happy to give some analysis about what I think you should do, based on the above and possibly other factors, in an upcoming post.