True classic R & B and Soul is from the '60's through the '80's, people. With the '90's it became increasingly mixed (or contaminated, depending on your point of view) with rap/hip-hop. Don Cornelius stopped hosting Soul Train circa 1993 for a reason, namely, he didn't feel right hosting the 'new' music younger people were moving towards, where hip hop was the main accent. One of the members of the Whispers also said at the time, that rap had killed R & B.
Real R & B usually runs on a patient, love ballad melody that is sung, not ranted, whereas rap is a quick paced flow whose tone is typically boisterous or angry. It's not an accident that soul ballads then started to be called "slow jams" in the '90's (to signal to current listeners with short attention spans that it wasn't the dominant quick tempo hip-hop sound). Second-generation R & B of the '90's going forward is either relegated to second rate status, or treated as good mainly as it integrates hip-hop into its genre. Whatever one thinks about those developments, the '60's-'80's R & B that preceded it (which was not-influenced by rap) is the true classic version of the form.
) and spoke the truth always.