BGP analyzing tool

   Are there any available BGP analyzing tool that can be used to identify
details on best chosen path based on the BGP algorithm? NTOP can capture the
traffic info, but to analyze each destination to find the reason for selection
(local preference, no of AS hops, iBGP vs eBGP etc) would be hard. I need this
info to understand why a certain upstream is being more prefered than the
others. Thanks.