Well, I have to give my home field Lydd a prop. The tower is always very friendly and helpful. And calm even under high workloads. Taking the time asking arriving strangers if they need fuel and stuff (I know it's in their interest, but still). The cafe food is not amazing, but it will do the job.
Bembridge - only been once but they were rather friendly. And cheap.
Damyns Hall - really nice little airstrip close to London. Cheap and friendly and in the weeks very quiet. I recommend it for visits to London.
Did a cross country to Santa Barbara recently and the controller there went out of his way to help a non-native English speaker and US rookie like myself to copy his (for me) complicated clearance. He really took his time, slowed the R/T down and looked out for me. Nice people - hats off.