We investigate quark flavor signals in three different supersymmetric models, the minimal supergravity, the SU(5) SUSY GUT with right handed neutrinos, and the minimal supersymmetric standard model with U(2) flavor symmetry, in order to study physics potential of the present and future B factories. We evaluate CP asymmetries in various B decay modes, Δ m_B_s, Δ m_B_d, and ϵ_K. The allowed regions of the CP asymmetry in B→ J/ψ K_S and Δ m_B_s/Δ m_B_d are different for the three models so that

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... cise determinations of these observables in near future experiments are useful to distinguish the three models. We also investigate possible deviations from the standard model predictions of CP asymmetries in other B decay modes. In particular, a large deviation is possible for the U(2) model. The consistency check of the unitarity triangle including B→ππ,ρπ,D^(*)K^(*),D^(*)π,D^*ρ, and so on, at future high luminosity e^+e^- B factories and hadronic B experiments is therefore important to distinguish flavor structures of different supersymmetric models.