This paper investigates objective choice and quantity competition in a generalized oligopoly model. The model herein is a two-stage game. In the first stage, oligopoly firms simultaneously and independently choose their respective objective (either profit maximization or revenue maximization). Then, in the second stage, they compete in quantity according to their objective. With linear demand functions and linear production cost functions, the results are as follows: First, the market size plays a crucial role in equilibrium outcome. When the market size is large (small) enough, all firms choose the same objective to maximize their respective revenue (profit). When the market size is moderate, some firms choose profit maximization, while the remaining firms choose revenue maximization. And the profit of the firms choosing profit maximization will be less than that of the firms choosing revenue maximization. Second, when all firms choose revenue maximization, social welfare and consumer surplus are both maximized, while it is a prisoner's dilemma outcome.