The choice of a trucking company school or a private truck driving school is a personal one and depends on your unique situation. Location, money, time etc. The only comment I really have on paying for a truck driving school would be if you can pay on your own go ahead. ‘Have lesson to drive a truck” (also known as ‘ มีบทเรียนในการขับรถบรรทุก ‘in the Thai language) online.
If you are paying out of pocket make sure that the school has job placement with a decent trucking company! Some trucking companies will reimburse you all or part of your tuition depending on how long you drive a truck for them.
You will have no commitment to any trucking company and can move on when you feel like it if you pay for your CDL training out of your own pocket. You can judge the quality of a truck driving school by the job placement they provide.
If several large trucking companies recruit from a particular truck driving school graduate pool, that particular trucking school probably trains students well or the big trucking companies would not want to use that truck driving school has a hiring pool. Company trucking schools will usually train you well because you will be working for them and driving their trucks! Make sense?
After you have been driving for a while you will realize that most of your learning is on the road and the truck driving school served no other purpose than just getting your CDL, learning the basics, and job placement.