Also, on topic, I got the impression that it was more, one person stands out, spren come to check the validity of potential surgebinder, and talk to their friend spren. Their friend spren decide to follow them in binding to knights and so find the closest suitable candidate for the spren.
I figured the skewing towards the kholin family was due to the honor Dalinar instilled in his children and also possibly his connection to the way of kings which the original knights founded their beliefs on.