It depends upon your interests/passion and career plans, and also what field or area of mechanical engineering you are interested in specializing in your Master’s degree.As well, what specializations are available at these universities will inform your decision.My sense (not based on any hard information) is, Germany may be a good place to do mechanical engineering degrees (even at low ranked universities) in relatively old (traditional) or related specializations (such as machine design, CAD/CAM, CAE, automotive engineering, acoustical or thermal sciences) whereas UK or Canadian universities may be a better choice for newer, up and coming specializations (such as mechatronics, MEMS, biomechanics or nanotechnology) or inter-disciplinary applied science/engineering areas.
You have to do additional research to verify this hypothesis.
what make you think that if you do not qualify for a top level university in Germany you would qualify for a top level school in UK or Canada?do you think the schools you mentioned have lower standards?
German universities use open admissions, meaning you cannot really not get in if you do it by the book.There is not really a significant difference between them in quality based on some foreign ranking, they are all the same.You surely are going to have to pay a lot more for Canada.
In my humble opinion, it is always best to learn in the best possible schools.I attended several of Canada’s top unis including McGill and top schools in the UK and US.