I find Mooper's posts well thought out, factual and both useful and thought provoking.
The main thrust of posts by him and others might be summarized as "Delta Skymiles works for me and may work for you". In this vein, here's my tally on Skymiles, compared to AA and UA & CO for me:
1. Skymiles' low level awards TATL in Y (my current focus) are 60k, while AA is 40K and UA is 55. That makes Delta 50% higher than AA, offsetting most or all or more than all of the earning advantage (if any) Delta has.
2. Delta low-level awards TATL are not available on the website calendars on as many dates overall as UA and AA. Anecdotal evidence but check out several months on the several sites and you may agree.
3. If low-level awards are not available, miles required jump faster on DL. The next level DL is 90K, while on AA it is 60K.
4. DL does not offer one way awards, while AA and UA do. This is huge for me as, using one way awards, I can take one airline outbound and another inbound, which has the effect of opening availability from one program to another. (I know DL does offer one way but only at RT prices, which I don't count).
5. DL's USA gateways are in CVG, ATL, JFK and SLC, so stopover possibilities are primarily in those cities. AA offers Chicago, New York and Dallas, and UA has DEN, IAD, Chicago and SFO. I have little interest in ATL, CVG or SLC.
6. DL's website calendar is unreliable. Statements about how 'if you have status and know how to tinker with the calendar you can then find flights', speak for themselves.
7. By Delta's admission, the calendar is broken. I think they said it would be repaired during the summer, so relief on that should be 75 days or less away.
I am really grateful that this thread has not degenerated into the partisan posts of others on DL worthiness. But on substance, I agree with Gleff-Of course I'll take cheap giveaways where I can find them, but when putting my earnings power or travel dollars to use, I have little reason to use Delta. And absent status or living in a DL hub, it's hard to see why others would do so.