This response is very helpful. I already have an idea as to how you should take it from here. I'm currently drafting it. The other thing I'm wondering is whether you at all plan to do other travel besides JFK-LAX, and also to which destinations you'd likely book your award tickets.

Flyertalk is an amazing place.

Other question: When are you beginning these travel patterns?

Although the JFK flights are much nicer - i'd consider flying into EWR on UA. Those flights are eligible for complimentary upgrades and many have the lie flat seats from the former continental international 757s.

False? EWR-LAX sees the occasional PMCO 752 with 16 lie-flat seats in F (read: fewer seats for upgrades). EWR-SFO/LAX are tough upgrades even as a 1K depending on when you're flying.

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.

Really, my gut feeling on what you should do depends partially on when you will begin (and potentially end) your travel schedule and how many elite qualifying miles and on which airlines you've already banked this year.

That said:

Based on what you're looking for, AA seems to be best (mainly and only after achieving Executive Platinum), and DL is not far behind, even though DL gets a bad rap for its difficulty with online award booking. UA would be more of a contender if it had upgrade potential, due to its ease of award booking (but remember that mileage accumulation is weaker). I know you mentioned that upgrade potential isn't as much of a priority right now but could be in the future... if there's at all a chance it will become a priority, then I'd recommend going with DL/AA if your regular, long distance flying is relevant long-term.

I could take my actual advice in several different directions, but it'll all depend on exactly when your new flying schedule begins and ends, and what happens after that. Please let me know.

The 125% earning rate as a Delta DM is mitigated by the difficulty in finding low availability awards, sadly. They don't call them Skypesos for nothing.

Yes, EXPs have a terrific upgrade rate (I've missed only JFK-SFO once this year out of about 90k BIS).

Importantly, AA systemwides work on any fare, allowing you to fly to Europe and back in business class for $440 (if you find the right fare ) as I did last month. UA requires buying at least a W fare (not excessively more in some markets), but DL is outright hostile.

The new lie-flat business class is rolling out next month, so I'm a very EXP right now.

If you're a 1K, op-ups on p.s. are not too rare. I had a very, very lucky string of 3 in August (out of 5 p.s. flights; the other 2 were instrument-backed upgrades at the time of booking). Nonetheless, hope is not a viable strategy for upgrades.

FlyerChrisK, excellent insight all around! I hope the OP will note all of your insight. I wish I flew enough to be able to be Exec Plat on AA and get those SWUs! Also, that's a great anecdote about your luck with op-ups on PS.

RE: your point about Skypesos, I agree to an extent, though I've seen a lot of DL opportunities for redemption lately. That said, I've learned more and more about Skymiles/partner availability over the years, and that kind of knowledge would be less necessary with AA/UA, which are, by default, much better.

I happen to think that, for me, AA miles are SO valuable, even more so than UA, because I am a coach redeemer. Their off peak awards and Citicard discounts come in handy for me. But most on these forums redeem for J, and the award charts tend to be similar across DL/AA/UA for J redemptions.

I'm looking forward to hearing more about the OP's travel patterns so that I can better identify a good plan of attack, if you will. Things change drastically if the JFK-LAX hop is only a few months long, 6 months long, a year long, etc.

What about Alaska (AS)? AS is partners with both AA and DL. You will be able to earn status with AS by flying both DL and AA. Wouldn't placing miles in an AS account also allow you have flexability with flight schedules?

I am asking these questions because I may switch to AS so that can place all my DL and AA flights into one program. I am also tired of the high mileage rates needed for DL award flight and AA is in the middle of economic and labor problems.

I hope my questions are not stupid. I just would like some expert opinions about AS since I have only flown them a few times. Thanks for any info.

You must remember that to attain the MVP/MVP Gold/MVP 75K status on partner airlines with AS it takes more miles than flying AS metal. Also for DL at least all complimentary UG's would happen after all DL elites have cleared and always at the gate.

Excellent post Yarhead. Very informative and thoughtful

EWR is a UA hub. They offer several options that only a major hub can provide. Even as a 1K, with global status flyers on board, upgrades are less frequent than they were with CO. (God, I miss that airline!)

but it all depends on where you live. Long Island - JFK.
NJ - LGA or EWR
Westchester - LGA or white plains

although have been hearing that Delta will be expanding offerings at LGA.

One important issue is what you wish to obtain when you receive a reward. Each of the major programs has its strengths and weaknesses as far as destinations are concerned, so the program that is best for awards to one destination may not be the best for other locations.

Upgrades will be nonexistant on JFK-LAX if crediting to AS. DL offers complimentary upgrades for AS elites (as mentioned); AA does not.

If booking an award with a Skyteam partner of AS (including DL), you still need low availability for DL to book this.

AS also only permits a single partner per award, so you can't do something like fly to Europe on DL and fly back on KL.

Presumably these will be put to rest sooner rather than later?