Dose-finding studies are a critical part of the drug development cycle in oncology. Between the severity of the disease and the typical toxicity of the treatments, oncology trials need to start human research at a lower dose level and then move up and down through some dose levels in a process called dose finding that helps determine a safe dose level. The toxicity of these oncology drugs is always assumed to increase with dose. However, unlike in chemotherapies where drug efficacy increases with dose, in many of the immunotherapy oncology drugs, the efficacy does not always increase with dose. Thus, it is imperative to find the optimal biological dose (OBD) that considers toxicity and efficacy and maximizes the risk–benefit trade-off of the drug, using a suitable dose-finding design. In the last 30 years, many different early-phase dose-finding designs have been proposed to determine the dose of the study drug that can be used in later-phase trials. The traditional 3+3 design in oncology was used for many years to find the maximum tolerated dose (MTD) for chemotherapies. In recent years, several different model-based, model-assisted, and algorithm-based designs for dose finding have been developed, some of which also incorporate efficacy to find the OBD considering toxicity and efficacy. The variety of current dose-finding designs has resulted in a bewildering array of options. We have reviewed the current commonly used oncology dose-finding designs and have provided a cross-comparison to guide future early development oncology research. We have produced a clear, concise set of guidelines on how to best choose the dose-finding design based on the characteristics of each drug studied.