This will depend in large part on what you hope to achieve. Both Krav Maga and Muay Thai have a particular focus. "Which is best" type questions do not work on Stack Exchange. "Which is best for this thing I'm trying to achieve" do work.
I won't discuss the relative merits of Krav Maga vs Muay Thai, since each has a particular focus that it is best at. However, if your ultimate aim is Kali, on the surface I would say that Krav Maga would suit you better since it at least includes anti-weapon defenses. The caveat to this is that you may learn techniques that fit in with a Krav Maga mentality and methodology, but which do not work for Kali. You will then find yourself in a position of having to re-learn what you thought you knew.
Although there may not be a Kali school near you, you may find Kali or Escrima seminars being given in your area. Ask around at local dojos. A lot of the taekwondo, karate, kung fu, etc... schools in my area also host Kali seminars. It is relatively rare to find a specifically Kali school. You may, therefore, desire to practice a supplemental art that will keep you in shape between seminars. Which one you choose will depend on your fitness level, fitness goals, and individual preferences.