This is a complex question, cause sure Muay Thai is a sport with limited rules, and Krav Maga is designed for street-defense/urban warfare, BUT if you have a Thai fighter with a record of 20, 30, 40+ fights in the ring (which most do) you best believe the Thai fighter is gonna send you to the hospital and will have the advantage. Take Boxing, yes it's a sport but who honestly here or in a bar has the skill and fighting experience to take on Roy Jones Jr. in bare-knuckle street fight? Now of course the reality of weapons comes into play in a street fight and Krav Maga practitioners obviously have the advantage here since there training includes weapons defense and multiply attackers. IMO if the street fight includes weapons and multiple opponents then the Krav Maga practitioner is better prepared without a doubt!!! Yet in a street fight having fighting experience (ability to take a hit or multiply hits, ability to fight hurt, in pain and take punishment) is important and this is where Muay Thai has the advantage. In NHB, Muay Thai has proven it's self to be the most effective striking style period and Krav Maga is NOT designed for the ring. Overall each has it's advantages and as a result the best formula is to cross-train!!!