I would say that most of the AFF trainers are good (they just need to). The only issue here is that I'm not aware of any english curse. I'm jumping with PLStefa in Elbląg and Gliwice but their website is in polish only (however most of the trainers do speak english). Maybe it's a right choise to complete AFF training anywhere and then just start jumping wherever it's cheap.
PS. Flying in Spain is an good and cheap option too! https://www.skydiveatmosfera.com/