I would definitely go for Aer Lingus.
Assigned seat at check in, no charge for check in (RyanAir even charges you to print out your boarding pass at home), ability to check in at the airport without incurring an astronomical penalty. Those are the only three I can think of for certaiin.
I've flown EI a few times and although they have a semi LCC business model (charge for bags and drinks on the plane) they still feel like a full service airline.
I have travelled several times with Ryanair but not yet with Aer Lingus.
Nevertheless I would look at Aer Lingus first.
Ryanair is my last option , I will only go with them if no one else is flying to where I want to go.
Ryanair seem to go out of their way to make it hard for their customers across many aspects of the process of getting from A to B.
I would go on convenience of the airport, and then price. Ryanair are fine and if you can get to you final destination at a fraction of the cost of a full service airline then do it.
Check both. Look at flight times and such conveniences. Also note that Ryanair does fly to 3 airports named Barcelona, whereof only one is actually in Barcelona - the other two, Reus and Girona, are 60-70 miles off.
Personally I'd go with Air Lingus.
I have flown are lingus and Ryanair, I much prefered are lingus, there was more room, seats where much more comfortable and felt wider as well.
Also as stated you have a seat number so avoiding mad scramble across the tarmac.
Unless there is a huge price difference I would take aer lingus.
Aer Lingus hands down.
Aer Lingus, although branded as a budget airline they are far from one.
Like others, I only fly Ryanair when I have to. My last flight to Dublin was from Birmingham, and there was a Ryanair flight and an Aer Lingus flight at virtually the same time from adjacent gates. The difference in boarding alone was noticeable.
The queue for Ryanair started about 45 minutes before the plane even landed on the inbound while we, with our assigned seats, sat comfortably and waited to be called. Staff patrolled the Ryanair line looking for any infraction they could penalise.
Our boarding by seat row went smoothly, from the back of the plane. I was near the front, one of the last to board. Boarding on Ryanair started before Aer Lingus and there was still a short queue as I boarded, presumably because the first on the Ryanair flight were grabbing the seats nearest the doors making others wait to get by.
We pushed back first, even though we were scheduled 10 minutes later. than Ryanair.
Fare including a checked bag was about £10 less on Aer Lingus.
Ryanair alternatives, every time, even if it costs a bit more. Price is not my first consideration. It either has to be a really good deal (for example £16 return per person to Pisa in May, total including all the fees they normally add on) with hand luggage. BA would have been £90 including luggage. So for this trip, I'll use Ryanair, but had I wanted checked luggage, and had Ryanair not been having a sale, BA would have been competitive if not cheaper.Edited: 11 April 2012, 9:53
I'd definitely go for Aer Lingus, just as I did in April 2011. I hate the idea of not having an assigned seat in advanced not to mention being subjected to Mr. O'Leary idea of service.
I have never flown Aer Lingus but if the price difference isn't too much and times are equally convenient I'd choose them over Ryan Air.
LeicsLad interesting that everyone kept seated and waited for boarding to start. My experience is that many people, even with assigned seats queue well before boarding starts.