EDIT: In typical pprune style (well, Jet Blast, anyway) I posted the following without first properly reading through the thread, and so have repeated comments already made by others. I am not impartial about Skysport either: Roger Hayes sent me first solo on one of his lovely Pups, and I'm still a member, but I'm not commercially involved, so please take this as a satisfied punter's plug rather than an advert.
EDIT ends
I agree with all of the positive comments about White Waltham. I didn't learn there, but it's now my base airfield. The runways are indeed bumpy but it all adds to the fun (since I've started flying big-up tailwheelie stylee, I don't think that I've ever positively rotated from a Waltham runway: I just get kicked airborne at some suitable juncture).
I have rather negative views about Elstree as a place (grotty runway, EFATO nightmare, mad "circuit", grumpy FISOs, zero atmosphere), but, and it's a big but, you can rent a Beagle Pup and a Bulldog there, which is worth doing if you've only ever tried Cessnas/Pipers. You can also rent another Pup and the same Bulldog from North Weald (the Dog shuttles about). NW is a most frabajalistic airfield, but is maybe a bit more of a schlep by public transport (Tube to Epping, then taxi, whereas Elstree is train to Watford, then taxi).
Another plus point about Elstree is that it stays open until sunset and it even has lights if you fancy the courageous stunt of night flying over populous areas. During the summer months it is possible to do a full day's work in central London and still get a reasonable bit of flying in before Elstree closes. You can just about do this at Waltham also, depending on where you start from.
My only criticism of wonderful 'Weald is that it closes a bit early. This is not the fault of those who run the place: the local Council owns it and is a bit strict on operating times, as it is on using the secondary runway on Saturdays, even when the main runway is crosswinded up the wazoo. OK that's two criticisms, but otherwise it's great.
[ 25 September 2001: Message edited by: FNG ]