I would say the answer really is which ever one is on the market at a price you can afford. There are several that have come on the market (they tend to become available for less than a day)
The miners are the big deciders in Bitcoin. They make most of the money, and the ones who ultimately make the decision on what new code gets accepted. They join their miners to the mining pools who support the policy they want. The miners want to make money forever. They want their coinbase block reward, as well as transaction payments. When the coinbase block reward goes to zero, transaction payments are going to be the only way for them to make the money they need to keep running their operation.