You really have to look at the earning and the redemption for each airline and then consider your own travel patterns for earning, and for redemption. No two travellers will be alike.

For instance a business class long haul may be 85,000 with Aeroplan, or 105,000 with United. Flying the same carrier on the same route may result in different earning for different people.

If your earning and redemption patterns tend to stay consistent from year to year, then not too much difficultly in making a choice. If they vary, then it may make sense to shift sometimes, as I do between the three I noted above.