There are some good business class deals from Dublin to New York JFK at the moment. The cheapest is available at £1108 (€1266) on Delta.
If you would rather fly on a One World carrier, they are almost matching these fares.
The AA direct flight from DUB to JFK, coming back via LHR, comes in at £1216 ($1556), booking on AA.com, sample routing and dates below.
However, if you book on BA.com and prefer to route via LHR you can pick up some BA sectors and mix and match with AA across a variety of options. The prices for these flights come in at £1144 (€1309); again, sample routings and prices below. I’ve included the direct DUB-JFK outbound, but there are lots of options around the same price point.