This does not answer your question directly ... the placing of the speakers on a shelf inside a built in (enclosed-?) bookshelf unit is as much of a determinant on your speaker selection as the actual specific speaker models themselves. Make sure that the speakers, if ported, are either front ported or provide you with foam plugs to fill the rear ports. You can also try to track down acoustic suspension designed speakers. My apologies, I do not know if the B&W's or Paradigms are rear ported, I seem to remember that the PSB Image series had this type of speaker placement in mind. There have been a few threads about this recently. Here's one of them ...
http://forum.audiogon.com/cgi-bin/fr.pl?cspkr&1057176870
Regards, Rich
http://forum.audiogon.com/cgi-bin/fr.pl?cspkr&1057176870
Regards, Rich