Deep learning (DL) techniques have recently been applied to anomaly detection (AD), yielding successful outcomes in areas such as finance, medical services, and cloud computing. However, much of the current research evaluates a deep AD algorithm holistically, failing to understand the contributions of individual design choices like loss functions and network architectures. Consequently, the importance of prerequisite steps, such as preprocessing, might be overshadowed by the spotlight on novel loss functions and architectures. In this paper, we address these oversights by posing two questions: (i) Which components (i.e., design choices) of deep AD methods are pivotal in detecting anomalies? (ii) How can we construct tailored AD algorithms for specific datasets by selecting the best design choices automatically, rather than relying on generic, pre-existing solutions? To this end, we introduce ADGym, the first platform designed for comprehensive evaluation and automatic selection of AD design elements in deep methods. Extensive experiments reveal that merely adopting existing leading methods is not ideal. Models crafted using ADGym markedly surpass current state-of-the-art techniques.