You need to be at least a Silver Medallion to buy a SkyClub membership, and for me that requires a combination of my short-haul business flights and some spend. Given the way they've structured these cards, only the Reserve card gives decent return towards MQDs, so if I stayed with Delta I'd have no choice but to keep my Reserve card if I wanted to get to Silver, despite 12 flights a year on Delta. The math doesn't math: $695 for a SkyClub membership PLUS $550 for the Reserve card, offset by just one hard to use companion pass?

Compare with American: $595 for an Executive card that gives a 10,000 Loyalty Point bonus after you hit 50,000, which effectively reduces the threshold for Platinum to 65,000 points/year, plus priority check-in and boarding, plus maybe $200-$300 in credits, vs $1245 for a unlimited SkyClub membership plus a slight bump in priority for upgrades except that MMs now beat that out and a hard to use Companion Pass?

Plus: Admiral's Clubs have recently upped their game on food, and you get unlimited visits + 2 guests for free. Given my flight and spend patterns, with all the ways you can earn Loyalty Points I have a reasonably easy shot at attaining Platinum status, which gives me access to business class lounges internationally. On Delta even with a Reserve card and 12 trips a year, I can just barely make Silver Medallion which is good for pretty much nothing more than upgrades on some short-haul flights. AA has a partnership with Hyatt which is my go-to hotel and AA miles are infinitely more valuable for international travel. I've already done the instant status match to Platinum Pro so I'm a Platinum Pro AA flyer for the next four months and targeting retaining Platinum status.

It's a no brainer for me. Despite the much less good route coverage of AA vs Delta, I'm headed to AA. Delta just doesn't make sense for me. I don't think this move is going to be a net positive for Delta, despite the various analyses above in this thread.