Airlingus mileage program
 

I'm a medallion member with Delta Airlines and absolutely love it. They upgrade me to first class upon availability at check-in, and really like the rewards. However, now I'm moving to Ireland, and should consider joining another network....airlingus perhaps? They have partnership with AA, British airways, etc. Do they have a good mileage program? Thanks!

I think you're thinking about it the wrong way. What routes are you going to fly after you move to Ireland? You decide which airline(s) fit your travel best, and then go with that airline's FF program or an partner program that you can collect the most FF miles from the flights you're going to take.

I'll be flying to the US and around Europe mostly.

Aer Lingus drank the Kool-Aid a couple of years ago and decided to become a low-cost carrier a la Ryanair instead of a major international carrier. Its frequent flyer program was never any great shakes, and since its departure from the Oneworld Alliance its mileage "earning and burning" prospects have taken it in the neck.

If you're a Delta medallion member, I'd just keep it, and use various Skyteam members for your longhaul and European travel, e.g. KLM, Air France, Alitalia, Czech, and so on, crediting your miles to DL.

And you may find yourself using Ryanair most of the time for intra-Europe travel. No need to worry about FF miles and upgrade there!