Strange, I have found the opposite with 1-Time...inside the aircraft ok, outside...not so.
Have flown Mango twice and found no hassle, except that they are SAA (in my mind anyway) and I found the legroom oppressive, though by removing the safety card, you can double it....
They are really all much of a muchness, except for Kulula, the biggest joke of all. Kulula is for the unemployed, or aimless wanderers, because if you have a time or place or need to be ( yes, even place) , you can forget about it. Will not get into how many clients, potential or otherwise, they cost me when my comany insisted on booking with them, due to my complete inability to keep appointments. Cheap at first glance, but very very expensive in the big picture.