The Sonny and Brownie version is very good imo.
I am not surprised Bonzo likes Donegan, it is in line with some of his other musical tastes, the shadows, hank marvin etc, each to their own. BONZO says
The Leadbelly version of Rock island Line is quite weak and awful compared with our Lonnie's version.
My opinion is Lonnies version and his attempts at american accents is reminscent of bands who engage in mock irish accents, i think his version is quite weak and awful.
I reserve the right to give an opinion , just as Bonzo has a right to state his opposite opinion.
they are just subjective opinions. however i do acknowledge the importance of Donegan in inspiring many youngsters to take up music that was very good, he was an inspiration to many.