Passed my PPL with Sussex Flying Club and havent got any complaints with them.
Good availibility even with very short notice (I used to ring up if I finished work early). They've put their prices up since I was there but I still think they are competitive.
They seemed friendlier than the other schools around Shoreham but cant speak about Pheonix as they were not up and running when I did mine.
My advice would be to visit them all and have a quick chat with them to see what each one feels like. You can do this in one visit!