@ chinny,
I don't think that you can really say any province is best for pharmacy or public health. All are good, depending on where exactly in the province you are willing to live. Canada as a whole is big on public health but you need to clarify what you mean by public health program manager. I say this because the public health here is far more developed than what we have back in Nigeria and there are a lot of sub specialites within public health itself. Of course you earn more with the sub specialties than within the general public health, but then you also have to spend some money on recertification and studying for exams to work in these sub specialities. It all depends on what you have. One thing though, don't expect your public health experience In Nigeria to really count for much here. you may have to volunteer for some time to gather Canadian experience for yourself which is what you can use to get a job.
As for pharmacy, pharmacists are everywhere people live and you may actually have more flexibility with pharmacy than with public health. I am in the same shoes as you. I am a pharmacist with a degree in public health. I had initially decided to work as a public health professional here and avoid the whole wahala of pharmacy exams when I was leaving naija, but on getting here and seeing all the options, I decided that pharmacy was a faster route to an assured job with good pay than public health. Of course the probability of getting jobs is much better in less populated areas but the choice is yours whether you want to stay in congested Toronto or Calgary or move to other areas like Ottawa, Kanata, GTA etc.