We are looking a a good thermal conductor. From online search, these are the list (ref. 1)

• Acrylic (0.2)
• Alcohol oil (0.1)
• Aluminium (237)
• Alumina (30)
• Boron arsenide (1,300)
• Copper, pure (401)
• Cotton (0.23)
• Diamond (1000-2000)
• Fiberglass/foam glass (0.045)
• Graphite fibres (1000)
• Polyurethane foam (0.03)
• Expanded polystyrene (0.0045)
• Manganese (7.81)
• Nanotubes (3000)
• Water (0.59)
• Marble (2.94)
• Silica aerogel (0.02)
• Snow, dry (0.25)
• Teflon (0.25)

Characteristics

• Thermal conductivity, k, is substance ability to conduct heat
• SI unit is Wm^-1K^-1, where higher value denotes higher conductivity

Reference

1. List of thermal conductivities (https://en.m.wikipedia.org/wiki/List_of_thermal_conductivities)