Spot Instances are the most suitable option for a workload with variable start times that can be interrupted and seeks to minimize costs, especially in a non-production environment. Spot Instances allow customers to take advantage of unused EC2 capacity at a reduced cost, up to 90% off the On-Demand price, with the caveat that the instances can be reclaimed by AWS with little notice if the capacity is needed elsewhere. This makes them ideal for flexible, interruptible workloads like development and testing. On-Demand Instances are better for workloads requiring immediate and uninterrupted capacity. Reserved Instances and Savings Plans provide cost savings for predictable, steady-state usage, but they come with a commitment, and they aren't typically the best fit for unpredictable, sporadic workloads that can tolerate interruptions.