CapedVulture,
Up until 6 years ago or so, there were many . . . . . regrettably, the way the company "culture" is headed it is difficult to argue a case for preferring one over the other nowadays.
Those who now find themselves working on the Irish AOC with HR administered by OSM (UK & Spanish bases ) are finding the contractural/rostering issues a bit trying.
Union recognition & the establishment of a CLA will help, but it won't turn the clock back to the conditions enjoyed ( & being dismantled year by year ) by those up in the Scandi bases lets say 6 years ago, before the opening of the HEL base started the downward spiral.
With Ryanair you have a fixed roster, massive potential choice of bases, and, if you can live at your base, spend every night in your own bed. The softening in company culture towards pax, appears to be slowly trickling down to the staff, but it will take a long time to turnaround that supertanker.
NAS, you have none of these, a little more money, and inflight wifi that officially you cannot utilise in the flight deck. Recent entrants have enjoyed some unrequested unpaid leave/forced 50% roster, and/or had to put up with forced base changes over the Winter.
If you join NAS you can also look forward to flying "long-haul" again, even as a 737 driver. Already Cork-Boston (with a 738 ! ) & the arrival of the MAX will see the network becoming more "intercontinental". . . . Oh the joy of being stuck in a pokey 737 cockpit for 7/8 hours on a regular basis.