First is a somewhat rare apple on the MCO-route. BC on the other hand is very common and thus can really make your pick based on your needs, likes, wishes etc.
Have been flying BC for some years now due to medical reasons. My opinions? When just looking at the standard BC product (so not taking into account the special needs stuff) my personal favorite is Aer Lingus. VERY good product and VERY affordable compared to it's competition (for instance you can get AMS-MCO as low as 1400,- where other airlines start at 3100). Good seats and seatpitch, small BC cabin and very good ratio crew versus passengers so I'm finding attendants basically either constantly around me or keeping an eye out and already being into action before I can decide I am indeed in need of...... fill in the blanks. Also like the fact that EI rotates their crews resulting in them having to work both BC and ECO on different haules, seems to be a lot less FA arrogance (and downcrease of service) I have seen with some airlines when FA's have done BS for too long. Food service also best but obviously personal taste and lounge at DUB is very good. At MCO it's the United lounge.
Another bonus of EI is preclearing US CPB at DUB airport, so you arrive at MCO as an national flight and can proceed right on your merry way instead of clearing customs first. DUB airport, well what can I say? Never seen such a quite, empty airport. Refreshing instead of the normal load mobs.
The EI BC product is so populair amongst both tourist, FF and business flyers that is does come with that as a downside. Unlike the "average" experience, you can find EI BC is sold out or close to it months before departure. For instance, this year I didn't get to book my trip (leaving sept 29th) until march of this year. Had to seriously play around with the dates to get proper availability and ending up having to change dates quite a bit (no problem for me so no biggie). On the other hand; the cheapest ticket for this flight was just over 1400,- and earlier july it was still only 1800,- with I think 2 seats left. An increase in price that is much more modest than I generally see with competition when seats are starting to get sold. Because of it's popularity, EI has published they will fit some routes with larger BC cabins, including their flights to New York and MCO. How that could influence price, availability and the product itself will have to be seen at that time.
All in all it's fare to say that I am very happy with EI BC, in case it didn't show.
Do not like Uniteds product, so have sadly said goodbye to my beloved Continental. KLM sucks, but then again what's new? Lufthansa, what shall we say........ does not protect the integrity of the product. Product in and of itself can be very good, but found some inconsistensies which I do not care for when paying the BC fare. Service........ should be good as long as you are an average Joe passenger. Avoid them like the plague when flying with a disability. Things have gone so sour and apparently it is so much the standard that quite a few crew members on both our inbound and outbound asked me and some more resembled begging me to file a complaint, incl. the captain on one flight. All I can say is I totally understand them.
Biggest thing really is what your personal wants, needs etc. are. Options like lounges, food type, entertainment, seat, size of cabin, flight schedule, type of aircraft etc. etc. can and will make the difference on what is the best airline for your trip.