I have travelled on both Thomsonfly and XL recently, and found both to be perfectly fine for what we needed. Both have leather interior which was confortable (much more than First Choice short-haul in my opinion) and the usual in-flight entertainment. I've booked to go away to Benidorm in July this year, and chose XL once again, mainly because of the price, but I also found their booking process to be very quick and efficient. Delays happen to all airlines, so i think which ever you choose you will be fine with.
Enjor your hols in Menorca! Flying is way much fun than driving
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!
Suddy