I'm really confused what to use for serverside pagination, filtering, sorting etc. which is good to use (jquery-datatables, ajax-datatables-rails or filterrefic gem.
Filterrific is a rails engine that hooks into middleware for filtering and pagination stuff, if filterrefic itself depends on kaminari for pagination and other gems for other functionality, so, if your app is not so big and possesses less traffic then it's better to use filterrific since it's easy to use and bundles all filtering, paginating, sorting concepts, if traffic is high consider using gems or build your own required only solution.