My my needs and my rig is both served well for 2.0, 5.1, & Dolby Atmos (5.4.4). My center channel is a Heresy IV. The L & R are Cornwall IV's. The surrounds are two stacked pairs of sealed box Bose 901's. In ceiling Speakers are two way 8" Klipsch's.
L & R Amplification is Black Ice Audio F100 Monoblock's fed from an Onkyo PR-SC5530 A'V Preamp (2.0 channel always Pure Direct via the XLR inputs).
Center & Surrounds powered by a custom "made by me" 3 channel Orchard Audio Ultra Amplifier. The height channels are powered by Emotiva BasX 4.0 Amp. DAC is PS Audio DirectStream Sr. DAC (MK1). Phono Preamp is PS Audio Stellar.
I always feel that one should follow the THX method regarding the CC Speaker. Either mounted vertically and the same model number as the L & R Speakers of least a bookshelf variant of the L & R Towers (if they aren't bookshelves anyways)