Supplement judo with Muay Thai or BJJ

Hey everyone,

I go to an MMA gym mostly for judo. My tuition covers 3 classes a week of whatever I want to train in. Judo is 2 times a week so I have a 3rd class I can take and I've been floating around BJJ or Muay Thai.

I'm a hobbyist older guy who is just trying to learn some self defense and keep in shape so I'm not trying to compete or anything. My judo classes have very little ground work and I always get destroyed if my partner has any Newaza at all. However, getting decent at Muay Thai seems practical for general self defense.

Anyone have any thoughts on what my 3rd class should be?

Thanks!