Having the right forging delegates is important for the network. Usually each public delegate offers a share in rewards, sometimes in combination with additional contribution to the network or project. Voting for the highest sharing delegate doesn't directly reflect in the highest rewards, we call this voter dilution (more info here).

Sometimes voting for a delegate that shares less in forging rewards might be more beneficial for you and for the project. A delegate can contribute to the security of the network or contribute towards marketing, community and product development, which could return in short term or long term a better value for the asset and project. You are advised to visit this page and DYOR on delegates before bringing out a vote.