Most two-car garage door conversations come down to three choices: basic non-insulated steel, vinyl-back insulated, and steel-back insulated. The best choice depends on noise, comfort, durability, budget, and whether the garage is attached to living space.
Typical R-value: very low, often around R-0 to R-2 class depending on construction. Cheapest and lightest, but loud and easy to dent.
Typical R-value: often mid-range, commonly around R-6 to R-9 class. Foam insulation with a vinyl interior face. Quieter and better looking inside than bare steel.
Typical R-value: often higher, commonly R-9 to R-18+ depending on thickness/foam. Stronger sandwich construction with steel inside and outside.