There are honestly many bands that he gave breaks to by playing them that resulted in bands getting record contracts. I don't know if you've read up about him so I will share this (forgive me if I am repeating something you've read) with you - Early in John Peel's career at Radio 1 (he was there from the start in 67) he was told he could only play X amount of records and he had to do other things during that time. He had the brainstorm to have bands come in and play live. This was the start of his famous Peel Sessions. Some unknown bands and later repeat and popular bands would come in and do a few tracks. The Cult, Fugazi, New Order and many others did Peel Sessions. See this
https://en.wikipedia.org/wiki/List_of_Peel_sessions for a long list of performers. I think he is the music fan that many would like to be, open. He wouldn't only play one or two styles of music and was open to various styles.