I think you are looking to quantify something that is beyond human quantification.
Non-reciprocal links are better, all other things being equal. Since not all things are always equal, you probably want a healthy mix of reciprocal links and non-reciprocal links.
Personally, I find it takes more time and energy to get reciprocal links of any quality, so I focus on non-reciprocal links, since they are better anyway...all other things being equal.