Krav Maga is nothing more than marketing and has genuine parallels with Crossfit. The entire content of KM can be found in the old Ju-jitsu budo scrolls from about 500 years ago. Literally all of it. What it does give you is a training context and Israeli flavouring. At its core however, it is a series of dirty tricks.
There isn't necessarily anything wrong with this - William Fairburn developed a very similar thing as a police officer in colonial Shanghai around the turn of the 20th century and was by all accounts very successful - he was simply teaching a method of dirty fighting. I would be very surprised if the entire content of KM wasn't to be found in Fairburn's work as well.
Muay Thai is a combat sport, and a rather rough one at that. Combat Sports like MT, Judo, Boxing, BJJ, wrestling - are always better than "martial arts". The reason is simply that they involve what is sometimes described as "aliveness" in training methods - full power training, sense of timing, sense of movement. Most martial arts miss out on at least one of these. Combat sports have full power sparring against an uncooperative opponent - which is the essential ingredient in learning to fight.
KM (and any other martial art) cannot involve full power training - it is simply too dangerous to practice, you would very quickly injure, maim or kill your training partner. The question, therefore is - how do you know a particular technique works, and that you can apply it in a live situation? A boxer knows full well that he/she can punch someone because they have done it thousands of times against an opponent who is trying not to be punched and is trying to punch them back. The same goes for a wrestler or judoka or BJJ person. They are trying to hold/throw/choke/armlock someone who is trying to resist them and also trying to beat them. With KM, you are by definition pretending to do a technique at low power on someone who is not actively resisting. The fact that you are screaming at them and swearing, really is neither here nor there.