ACGME works to establish minimum standards and IMHO they do a relatively solid job at that. This is one of the major reasons that I moved to the US for training - in Europe, there is great variation in training, from excellent to inadequate (even among different programs in the same hospital).
Once programs adhere to the minimum ACGME/ABS standards, they can customize the residency training as they see fit. Thus there can be significant differences in the training. Some programs focus on academics (i.e. research), other programs focus on clinical excellence, and others just have residencies for administrative reasons. Even in the clinical aspect, the residency is 5 years for everyone and there is a lot of ground to cover, so if a program is super strong in i.e. HPB surgery because the residents spend 6 months on the service, they are getting less experience in another field of general surgery. There is no program that is perfect in everything, and usually, if a program is a leader in one aspect, it trails behind in other aspects. You have to decide what's most important to you and then figure out what (type of) program would be the best fit.
Good luck!