What were the various motives of Progressive reformers?

The Progressive Era—and the reformers who populated it—sprung from dissatisfaction with the status quo of the Gilded Age. The laissez-faire, business-first attitude of many nineteenth-century politicians horrified a growing number of progressive reformers, who believed that people, not money, should be America's first priority.
The Populists and Progressive reformers shared many of the same motives (namely, helping the disempowered and working towards a balance of political and economic control between the wealthy and the poor), but they come from very different backgrounds and used vastly different tactics. The populists were primarily from working class cooperatives and unions, and used collective bargaining and striking to try and make change from the bottom up. The Progressives, on the other hand, attacked the problems from the top, attempting to change legislation, build charitable organizations, and create more moral communities.
Progressivism is difficult to discuss in general terms, as it was an enormously diverse movement, led by a wide swath of Americans with nearly endless motives and goals.
Some Progressives, like Oregon senator William U’Ren, went directly towards the motive of political reform, aiming to dissolve political machines and give people more of a voice in the legislature. Beginning in his own state, U’Ren passed measures that allowed citizens to propose laws in the legislature (1902), recall elected officials for misconduct (1908), and vote in “primary” elections to reduce the power of political machines (1911). These bills would eventually make their way to the nationals stage.
Other Progressives, like Eugene V. Debs, focused on the motive of easing tensions between the working class and the employing class by establishing labor unions and instituting collective bargaining measures. Wealthy Progressives also shared this motive, but used different techniques: industrialists like Andrew Carnegie created lasting foundations to fund programs in the humanities and sciences, purchased large tracks of land that were donated to the state, supported aid and education programs for immigrants and black Southerners, and even helped professionalize aid organizations like the Red Cross.
Progressive reform also became a popular pastime for the middle and upper classes. Women in particular took up the mantle of reform, particularly in the areas of temperance, suffrage, housing reform, and healthcare. Most famously, women like Jane Addams established settlement houses, situated in poor immigrant communities. Educated, civic-minded young women would live in these houses and provide free services to their communities, including classes in various fields, recreation, lectures, and childcare. They also conducted research into the community's social ills, and used that research to push for reforms.
Progressivism also owes a lot to the work of the "muckrakers," groundbreaking investigative journalists who worked to upset the power balance between the weak and the strong by exposing the true underbelly of government, industry, and social inequality. They were a diverse group, including women, Black Americans, and immigrants, and used new techniques—such as research, flash photography, and interviews—to reveal, for the first time, the reality of life in America. The muckrakers raked the muck up, and the Progressive reformers washed it away through legislation.