Dublin is quite a good idea, to avoid the usual 1.5 hr wait state side. A New York flight from Cardiff would be amazing and knock 30 mins off the flight too as it’s closer and quicker to land here rather than Gatwick.
I’ve not flow to the US from anywhere other than Dublin for a few years now.
Flybe from Cardiff to Dublin, then Aer Lingus or Norwegian to NY.
Clearing customs in Dublin is great, saves so much time.