So I stumbled across this
article about the knee defender thing from that pinnacle of journalism, the Mirror.
It includes a detailed section comparing legroom on different airlines which is, frankly, complete and utter rubbish. I mean, I don't expect much from the Mirror but seriously...?
If you fly long-haul in Economy, you might want to avoid Southern China airways as it's listed as having from just 29 inches of room. British Airways’ Euro Traveller is not much better with just 31 inches on most of their planes.
The top airlines to go with in Economy are United or American Airlines. These have a whopping 36-37 inches of legroom.
For Premium Economy – or Economy Plus as some airlines call it - Condor Flugdienst and Gol (we've not heard of them either) are stingy on the legroom, with just 31-32 inches. According to SeatGuru, the best is OpenSkies which has a generous 47 inches of legroom.
If you prefer flying Business, the ones to avoid are Brussels Airlines and Lufthansa as they only give you a paltry 30 inches. The best in this case is Thai Airways with 87 inches of room.
[Mods feel free to move to somewhere more appropriate]