I don't know if the ACUC open water/AOW courses are more intensive than PADI, where I took them (Israel) there are diving laws that require the courses to be a certain length and certain number of dives. Having taken the rescue course in Canada, without the diving laws, the ACUC course involved slightly more work, including a snorkel rescue of a diver in full scuba gear, which was one of the most difficult rescues, having no air, obviously. The PADI course didn't require it, and one of the people taking the course had no desire for ACUC certification rather than PADI, so he got to go home early.
As far as Divemaster courses go, you want anything but PADI - I know someone certified in Canada who wanted to take an AI course in Israel (through TDI/SDI), and they made him retake most of the classes and dives for that course, as well as writing the exam (NAUI Master Diver, not even rebranded yet with the TDI/SDI logo on top - which isn't made any easier in some places if you work in metric and don't know the local language, as the English version is American-Imperial), before they'd let him go on to AI. Maybe it's just politics, having not taken the Canadian PADI divemaster course, but maybe it is significantly different.