The large ecosystem is one of the biggest benefits to Ruby/Rails development but, yes, it can be difficult to determine which third-party project is best supported or most popular. I'd have gotten lost long ago if it wasn't for Christoph Olszowka's "The Ruby Toolbox" site [1] with its grouping of projects by category and sorting by GitHub watchers, forks, and recent activity. Take a look if you don't know about it already.

[1] http://ruby-toolbox.com/