The longest but most professional is GulfAir by far. Three meals aday at the movenpick hotel,very friendly. Qatar s can go anyway depending on who you get, not really standard. You stay at Ramada and pay for your own meals.
Emirates very good as well,hotel no so nice as Gulf Air, the rest is the same, but I rate Gulf Airs Much better.
Bye the way I passed all three interviews.
No info on Ehtihad,