In my opinion the most successful contemporary coach is Dav Whatmore.
He converted an average Sri Lankan outfit to win the World Cup and was largely instrumental in changing their performances and fortunes in Test cricket. He has had moderate success with Bangladesh.
He also had a successful 2 year stint with Lancashire in English County Cricket (Something JB was unsuccessful at - attributed to his inability to get along with members of the Middlesex Team at the time - resulting in his contract being terminated IIRC).
He converted an average Sri Lankan outfit to win the World Cup and was largely instrumental in changing their performances and fortunes in Test cricket. He has had moderate success with Bangladesh.
He also had a successful 2 year stint with Lancashire in English County Cricket (Something JB was unsuccessful at - attributed to his inability to get along with members of the Middlesex Team at the time - resulting in his contract being terminated IIRC).