One of the excellent resources I have used when purchasing Plarail is Platetsu's top ranking guide. So, for those who are looking for resources, here are the following:
Platetetsu's Plarail Ranking
Platetsu's Thomas Ranking
Platetsu's Usability of Rails and Scenes Ranking
Platetsu's Plarail Advanced Ranking
And for those who are looking for the top selling Plarail of the week in Japan
YODOBASHI PLARAIL RANKING
BIC CAMERA PLARAIL RANKING
