This paper presents an evaluation of two families of ring-based algorithms implementing the Eventually Perfect failure detector class (P). The evaluation is based on two kinds of performance parameters: communication efficiency, which refers to the number of links that carry messages forever, and quality of service, which includes the capability of the failure detector for providing right answers as well as reaction and initial stabilization times. The first family of algorithms includes several communication-efficient implementations of P introduced in a previous work. For the second family, introduced in this work, we start from the design of a non communication-efficient Q algorithm, and then we apply a transformation to obtain a P algorithm, including some optimizations to improve the quality of service.