In my opinion Corporate free speech and unlimited corporate spending does not favor anybody. The people do not benefit, the community does not benefit nor does society at large. Even the corporation suffers from the pitfalls of unlimited spending. As an example, corporations have been dumping millions into avoiding GMO labeling on food and beverage products. This serves the best interest of no one.
No, unlimited corporate political spending favors corporations as the ability to spend is the ability to buy elections. Corporations, with their deep pockets, have the ability to spend the most money and thus to buy the most elections. This is very unfair to the middle class and poor, who do not have this money to spend.