We haven't reviewed the JBL LC2 (pictured here) or B&W CMC, but Tom Norton included the CMC2 in his review of a complete CM-series home-theater speaker system, and he liked it very much. Of course, the CMC2 is $1250, while the CMC is $600, and the LC2 is $500.
All that aside, the most important criterion for a center-channel speaker is that it tonally match the front left and right speakers. So I would get a center speaker from the same manufacturer that made your front speakers. Many companies offer several models of center speaker, in which case, I'd get the one that most closely matches the driver compliment of the main speakers. Perhaps the manufacturer recommends a particular center to go with your mains; if so, I'd be inclined to take that advice.
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