G4 is the recommended compression method for most high-resolution, 1-bit output. G3 and G4 compression options are not available if in an output process template:

• In the Render section, Spot Color Handling box, you select Convert to Process
• In the Calibration & Screening section, Screening System box, you select any stochastic screening system

Either of the above conditions can introduce stochastic pattern in the raster data, which can generate very large files when G4 compression is used.
G4 is a safe and recommended compression method when:

• You have CMYK data only and aren't using a stochastic (FM) screening system
• You have spot colors and are not converting them to process

ZIP is the recommended compression method when dealing with stochastic screening.