I've only been to English festivals (so far)Each one is different, so difficult to rank :
Cromer - folk on the pier - the main venue is in the theatre on the end of the Pier - hence many jokes about overseas gigs.
Bridgenorth, amazing range of music, very relaxed atmosphere. I discovered Alan Burke & The FOS brothers there.
Cheltenham - very civilised - excellent music - AND it's in february so it cheers up a dark/cold part of the year.
On downbeat note - the only festival I haven't enjoyed was this years Cambridge - far far too crowded.
Haven't been to Fylde/Sidmouth/Tonder ......
Just out of curiosity,does WOMAD count as a folk festival?
I'm already planning 2002 !