FreedomSmokeUSA's Flavor Range juices and tobaccos have selectable PG/VG (Specialties and Samples do not)
Gourmet Vapor - sign up there to get their infrequent but huge sale notices. Long delivery time but so cheap during a sale that it's worth experimenting (and it is an experiment since many juices are customer creations). I also create ones and I mark them private unless they come out well.
Juicy Vapor - lotta flavors, lotta sample pack configurations, all PG/VG selectable
Vapor4Life - their cartomizers are KR808D-1 cartos (you could try them with a 510 to 808 adapter - Blu is not 510 and its charger will fry a 510 and vice versa but it does have 306/510
threading.). I use a couple of their WOW juices (WOWbacco and WOW Vanilla) and they are thin and clear - like the thickness of 90PG/10VG or so?
Velvet Vapor - their Raspberry Gingerale is very good