This chapter delves into the significance of choosing the most suitable Physically Unclonable Function (PUF) design for various devices and applications, especially in the realm of security and cost efficiency. It assesses different PUF implementations based on performance metrics such as scalability, area cost, and resistance to modeling attacks. It explores the integration of PUFs into IoT devices and other resource-constrained systems by balancing security requirements with hardware limitations. It provides detailed comparisons between various PUF architectures, including Arbiter PUF, XOR PUF, and others, to assist designers in selecting the best fit for their specific applications. It concludes with implementation results and a comprehensive comparison of PUF designs in terms of area cost, reliability, and security.