Ooh, I'm always on the lookout for RY4 recommendations. If I hadn't stumbled upon TPA RY4 Asian, I doubt I would still be vaping. I didn't like TPA RY4 double - too sweet, or TPA RY4 - tastes of cloves, but their Asian is glorious mixed anywhere from 4 to 10%. I use 5%. Hangsen's RY4 I didn't like at all. Pity, as I bought their 50ml bottle.
TPA Asian is also very nice with a little menthol added.