When should I buy a rotomolded cooler instead of an injection-molded one?

Only if you need ice to last multiple days in hot weather — like off-grid camping for a week or living somewhere that hits 100°F. Rotomolded coolers are thicker, seam-free, and stronger (you can stand on one), but they’re heavier and more expensive. For a day trip or tailgate, injection-molded is lighter, cheaper, and good enough.