Authentication and cryptographic key generation mechanisms are used in a broad range of security related applications. While there have been substantial efforts among the security research community, challenges in implementation methods for authentication and cryptographic key generation still prevail. With inherent irreplicability, Physical Unclonable Functions (PUFs) provide a new solution to security challenges. However, designing a new PUF or finding an appropriate existing PUF for each new security application is not an easy task, and it requires a set of particular properties to suite particular application. Thus, a thorough experimental study of numerous PUFs can provide useful information on different properties of these PUFs. Moreover, PUF development researchers can utilize the study results to design new PUFs with enhanced properties or to overcome deficiencies of existing PUFs. This paper is an effort to implement a group of state-of-the-art PUFs on two models of FPGAs and also to carry out an experimental analysis that evaluates the implemented PUFs. Our study focused on two major classes of PUFs: path-delay-based PUFs and frequency-variation-based PUFs with three designs in each of two classes. The experimental results provide useful information for security application developers to devise innovative PUF-utilized security applications as well as PUF design researchers to design PUFs for particular applications.