Performance parameters of tapered distributed feedback (DFB) and distributed Bragg reflector (DBR) lasers are compared with earlier configurations, such as uniform grating DFB, (lambda) /4 phase-shifted DFB and uniform grating DBR lasers. Parameters such as oscillation conditions (above and below threshold), mode pattern along the laser length, output power, effects of nonzero end reflections on oscillation conditions, yield of the gain, linewidth an differential quantum efficiency are obtained for tapered DFB and DBR lasers. To find oscillation conditions a nonlinear model is used, which considers gain saturation due to longitudinal field intensity variation along the laser. Grating shape is of rectangular type. For tapering profile, a class of polynomial curves of hyperbolic form with a degree of freedom is used. For the analysis F-matrix approach is applied. For purpose of comparison, a constant effective coupling coefficient for all structures is defined. Some new important results have been obtained which show that, tapered DFB lasers are superior to phase shifted DFB lasers. Improvement of tapered DBR over uniform DBR depends on the type of performance parameter.