I am a Foreign Manager here in China. I really don't feel that any of these courses have seperated the good teachers from the bad. I have some teachers that took the courses you mentioned, and have had to let them go. Some of them had just no clue at all. Others have taken the courses and do really well. However, those who tend to do exceptionally well, have some sort of experience. A teacher whose major work experience was a coffee house back home, but has a TESOL certificate, is far less desireable than the teacher with no certificate, but experience either teaching, or just working in a leadership role.
I always look for experience first, volunteer experience second, Name third and maybe the TESOL or Celta or whatever will catch my eye before I call them.
I strongly feel that these courses are far too expensive, and are a money making scheme rather than a furthering education venture. They say that jobs are guaranteed- just apply to China and you'll have a job, guaranteed. Even if you're a self proclaimed axe murdering child molestor. ( though not at my school! )

I would suggest not getting too wrapped up in it. Yes, some of the things that they teach you in the course are valuable, and helpful. However, a little internet research on teaching approaches, materials and lesson planning is cheaper and easier.

However, it's all up to the individual.
Good luck,
Candace.