LGW isn't too bad apart from the walk to some of the gates, and the queues at peak times at security.
LOS The new Virgin Nigeria domestic facility in the International terminal at Lagos has reduced the stress involved in travelling to PHC or ABV. Far superior to the existing domestic scrum over on the other side of the terminal.
The terminal at Kuala Lumpur is also very swish and modern with a good atmosphere.
I've had excellent short connections at CDG, AMS and FRA recently but I dislike FRA intensely due to its sprawl and poor signage. AMS and CDG are OK without setting the pulse racing, at least they have good facilities for coffee and food.
Overall the terminal I have enjoyed most is Paderborn, though it is some years since I used to visit it. Small but perfectly formed, and with a real aviation feel to it.