The choice of removal engine is determined by the property that distinguishes events the analysis cares about from events it doesn't:
Surviving events should be at least a certain size: Remove labels (smaller).
Surviving events should be no larger than a certain size: Remove labels (larger).
Surviving events should be at least a certain brightness: Remove labels (weaker).
Surviving events should be no brighter than a certain level: Remove labels (stronger).
Surviving events should overlap a known feature mask: Remove objects (without seeds), with the feature mask as the seeds. ("Drop events that don't contain a seed" = "keep events that do.")
Surviving events should NOT overlap a known feature mask: Remove objects (with seeds).
Compound criteria become chains. "Cells larger than 50 µm² and brighter than threshold X and in tumor regions" is three engines in sequence — each criterion expressed as one removal step.