The LCB/RCB issue depends on your tactics. A Pulis's team doesn't need to care about it. However, for a possession team with ball-playing defenders, left foot for LCB and right foot for RCB is the best fit for the defenders to play straight line forward ground passes through the gap of the first line of opposite players, as well as accurate diagonal long passes to the other sideline. That's why Louis van Gaal insists to play Badstuber and Blind in LCB over Lucio and Jones. But of course, LVG is clearly too mad on it that he forgets other factors needed to be considered.