If you are looking to redeem on a particular airline you may be better collecting on their program...most airlines will release more seats to their own members than they do to other *A partners.

Taxes and fuel surcharges tend to be imposed by the operating carrier so it 'should' not be any different redeeming on any program

Least miles required - often this is related to the earning miles so you may need less miles to redeem but you will have had to actually take more flights to earn these miles so the 'saving' is not real

Which airlines are you interested in redeeming with and which airlines will you be flying on to earn your miles...this will be key to choosing the best program for you as an individual