I hope this isn't too off-topic, but I'm in a bit of a dilemma and would appreciate some advice/perspective.

To note, I currently have 33k Starpoints, 53k UR points, ~85k AA miles (when statement closes), ~53k MR points, thanks to the SPG (30k), CSP(40k), AA Exec (75k), and PRG (+ another 100k when I hit the Plat bonus) respectively. I don't need to actively use all of these points, and would be fine with saving them for the future.

I'm presently in the area of DTW (Delta hub) until the middle of next year. I normally live in Philly (AA hub). I'm expecting to take at least 4-6 flights (round trip) before returning home, one possibly being international. My original plan was to focus entirely on AA since they fly out of DTW and there are a modest number of flight options. However, since I am going to be here a while and I'd have many more flight options with Delta (perhaps at better prices), is it worthwhile to grab the 50k bonus (via incognito) with the Gold SkyMiles card?

I don't think I could reach any sort of status with AA in this particular year, even though I'm supposedly signed up for their elite status challenge. Delta would be the same way, but having the SkyMiles card would also provide the priority boarding privileges, and many of my points can be used towards Delta/Virgin Atlantic flights (Delta flies out of PHL on behalf of Virgin Atlantic, as an aside). I also considered that the Platinum provides SPG Gold status, which will enable me to gain Starpoints for money spent on Delta flights.

I also debated trying to get the Citi Prestige card, but the transfer partners aren't super useful for DTW beyond Virgin Atlantic, and would be more useful if I was back in Philly. Once I hit the spend on the Platinum I'd be sticking with the Exec/PRG as my main two cards, since I still need to have a primary Visa or MC for when I can't use Amex. I have a number of other cards from the past few years, but I may be closing a couple of those which I won't ever be using again (Arrival+ and Quicksilver, specifically).