Rigid foam board insulation is one of the safest insulation materials for basement walls. The panels offer a moisture barrier to prevent mold and mildew build-up. At the same time, this material is also fire-resistant, so you don’t have to worry as much about a fire breaking out as you would with spray foam insulation. 

Fiberglass is considered a favorite garage insulation choice due to its combination of affordability, ease of installation, and overall effectiveness. Fiberglass provides good thermal resistance, helping regulate garage temperatures and minimize heat transfer. Additionally, fiberglass is moisture-resistant, reducing the risk of mold or mildew formation.

The best type of attic insulation depends on where you live, your budget, and what stage of construction the attic is in. For example, if you're building a house, then structural insulated panels are a worthy investment since they're easy to install during construction and they're the most energy-efficient type of insulation.  

Additionally, if you live in a very warm climate, then you can potentially save quite a bit of money by opting for reflective insulation, which is more affordable than comprehensive insulation but doesn't work well for cool climates. Blown-in, loose-fill, and spray foam insulation are all great options for attics in moderate climates.

R-30 insulation is better for higher thermal resistance, but whether it’s "better" depends on the application. R-30 is much thicker and suited for areas like attics or floors in cold climates, where more insulation is required. R-13, on the other hand, is thinner and works well for 2x4 walls or milder climates where less insulation is sufficient. Choosing between R-13 and R-30 depends on the area being insulated and the climate. For example, R-30 provides more insulation but may not fit everywhere in your home.