I agree with Elevick that having the LF/C/RF match closely is important for home theater, and this includes the tonality of the speakers. As far as amps are concerned, their tonal qualities are important, but in my experience the amplifier gains are also a factor that must be considered. Even if maximum power ratings are different, it is gain that will make an audible difference. The front three speakers must be an integrated, seamless tapistry of sound that should not draw attention to any one speaker (e.g. as sound travels L to R across the front, it should not change as it moves from L to C to R). If everything is not closely matched you will hear the speaker transitions. That said, I would use the three channel B&K for LF/C/RF, and then choose between the other two based upon gain, maximum power and tonal qualities for the LR and RR (compared to the B&K). Just my opinion, based upon my experiences.
Help deciding which amp to use
I have a Nakamichi Av10 and nak dvd and cd, von schweikert speakers (all of them are vs). Anyway, I am wanting to go with separate amps and use the pre-out on the nakamichi. Today, at the local thrift store I picked up a Rotel 2 channel amp and a b&K 3 channel, and a parasound that will need service but is 2 channel. I was thinking B&K f/c/r and rotel rears, and then eventually parasound r/l B&K ceneter/rears. Opinions, advice? I should get much better sound out of running those amps instead of the receivers amp, shouldn't I? About the thrift store, I have to do a little bragging- the B&K and Rotel were 75 bucks each working, the parasound was 25- were they nuts?!...hehe