Most reliable

Out of many free and premium wordpress plugins i used Geo-directory is something really flexible, stable and scalable.
Less features compared to competitors; But end of the day all of these extra fancy extensions are of no use if the base plugin is not reliable. Im using GD from almost a year now and there was no issues so far.

Only one suggetion i have is to activate support forum as inputs from the forum was helpful for experimenting and resolving minor issues oneself instead of reaching out to the support team by email.