Theravada contains the most original Buddha teachings and it was recorded in Pali. Mahayana developed more than 600 years after Buddha, it was written in Sanskrit and it contains many ideas not found in the original Buddha teachings. Tibetan came more than 1000 years after Buddha and it deviated even further from the original Buddha teachings eg. See the vast difference between Tibetan focus on devotion to their gurus compared to the original suttas that where Buddha advised us to be a refuge to ourselves. Better to stick to the original Buddha teachings in Theravada. Cheers.