The ideal ratio for a spinning reel depends on the type of fishing you are doing. Generally, higher ratios (5:1 or 6:1) provide more power and speed when retrieving lures, while lower ratios (4:1 or less) are better suited for slow trolling or jigging. For most general-purpose applications, a 6:1 ratio is recommended as it provides an optimal balance between power and speed. Consider the size of your line when selecting a reel; heavier lines require higher gear ratios to ensure adequate winding power.