Flew EI in Y JFK-DUB one-way just before xmas. I thought it was fine - meal service was ok. Would definitely pay for the seat assignment on EI. I also recall that the IFE options were pretty decent - although I also recall reading a book on that flight.

I would certainly prefer going via DUB (especially if US immigration included in the package here...).

Don't EI sell lounge access? Now, not sure how that would work with an award ticket. Lounge is ok, but nothing special. Doesn't that lounge next to security in the old part of the airport accept Priority Pass?

No recent experience of LH long-haul Y. Their lounges at FRA and MUC (the ones I've visited) are hardly worth the effort of climbing the stairs (where applicable) - certainly a sub-par experience. Otherwise I'm sure LH is generally fine and one cannot go too wrong with that option either.