Hi,
I have all three of these books.
I've used Book of Exalted Deeds more as there were two exalted characters in my epic game serving Raziel (one of the Celestial Hebdomad) and one, the monk, took the Vow of Poverty.
I've used only one spell, I think, from Book of Hallowed Might, and haven't used Book of the Righteous at all -- although it does have a cool pantheon in it.
I also have the Book of Vile Darkness and have used this quite a bit -- the last epic adventure I ran was set in the Abyss so I used some of the NPCs, plus lots of the spells and some feats. I've also used the spells in two other games -- it's a great source of evil magic.
Cheers
Richard