Really depends on your priorities. Is this a home theater under construction or a audio system that you want to enhance over time to also be a home theater. If audio is your priority... a sub. If HT then center channel.
Something like 85% of HT sound comes out of the center channel. So from a HT perspective really important.
Something like 85% of HT sound comes out of the center channel. So from a HT perspective really important.