There will definitely be a lot of arguments for and against immigrating to any country of choice, be it Canada or not.
The only point I want to make is for very many of us who are carried away by the enjoyment of Qatar. It is a peaceful country,family-oriented environment, very nice people and definitely, a place to call a home. No one would come to Qatar and would not wish to remain here. We all love it.
Though we don't pay tax in the real sense of it but we pay some money through other means which are not applicable in other countries; you know them.
Second point is this: No matter how settled and comfortable you are now,if your appointment is terminated today for whatever reason and your RP is cancelled, you and all that belong to you must leave, even if your children are writting exams. If you are lucky, you may get a respite to allow them finish their exams before you leave for the airport.

Most people who migrated to Canada did so, not because they love to pay tax (no body wants to), but there are other things Canada offer whivh are not here. There is no country in this world where you get EVERYTHING you want. This is no paradise. Therefore, whether you migrate or not is a personal decision but don't let the tax discourage if there are other benefits.

Cheers