I think Sanda is better if we just talk about fitness. The other three are not very familiar.
Sanda and judo are strongly recommended from a practical point of view.
Karate ... I don't recommend this, and I don't explain the specific reasons, for fear of being sprayed by those fans.
Jeet Kune do is ok and comprehensive, and it is the prototype of mma. But the actual combat effect is average. Although Xiao Longge is a fighting genius, he is from traditional martial arts.
But I'm from Beijing .. = = .....
As for the pros and cons:
Personally, I feel that Sanda undoubtedly has a fist advantage, and it is not a big problem to abuse street hooligans for one year.
However, although Sanda wrestles, its strength is far less than that of judo, which has ground wrestling skills (such as broken arms and legs, broken neck and blocked veins, causing temporary shock).
My buddy who practices judo+weightlifting, from a sports school (junior high school), is very sharp.
Sanda has the advantages of boxing and boxing, but melee judo is better.
I don't have much contact with the other two, so I won't talk nonsense.