Hello! I´ve used acridine orange from Sigma in the past and it works perfectly fine. Keep in mind that this staining is useful to detect acid vesicles but it is not an accurate way to detect autophagy, so you will need to combine this staining with other techniques to detect specific autophagic markers. The following link is from an extremelly useful guideline for autophagy detection.
Article Guidelines for the use and interpretation of assays for moni...
Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)