I guess the problem with a question like ‘which is the best’ is that most students have only been to one training establishment for ATPL ground school. Any one can say ‘I recommend so and so..’ but I assume very few have actually compared that directly to others. Any view is highly subjective…I guess it is best to add up all the information and see which matches your requirements the best. Whether some ulterior motives exist for certain posts could be another subject entirely. For my personal requirements, Bristol (distance) and ATA seemed the best suited to my needs. In the end I chose ATA, and I must say I have been entirely impressed. Go and visit the schools, speak to students who actually study there without staff present and make your mind up, see through the flashy adverts! Just because they suggest you will become a pilot, doesn’t mean you will make it. etc.
Good luck
,
Tom.