I can also recommend both Rock Star and Vaperite's VR4, but they are very, very different juices. Rock Star definitely has very discernible (and nice)
tobacco flavor while VR4 is a subtle
tobacco base that is more of a delicious smooth caramel.
The differences between these two illustrates just how vague a term "RY4" really is. The differences between RY4s from different vendors can be very substantial indeed.
Both of Vapor Station's RY4-types (RY4 and VS4) are good as well, but they have a flavor more reminiscent of BWB's Malty than the other two.