Avoid LTN (Luton) like the plague! A miserable place, 737's, lot's of "management" pilots and last but not least: ToiletTown/Luton itself.
I have frequently flown out of all 3 bases in the past and if I was forced to choose between LGW or STN, I would always choose STN, an ex-Go base, which means the atmosphere is a lot more relaxed when compared to LGW. Nice crews and fairly hassle free (for UK standards that is...
).
Just my 2 pennies...