Plasmon waveguide resonance (PWR) sensors are particularly useful for biosensing due to their unique ability to perform sensing with two different polarizations. In this paper we report a comprehensive performance comparison between the surface plasmon resonance (SPR) sensor and the PWR sensor in terms of the sensitivity and the refractive index resolution. Both sensors were optimized using a genetic algorithm to acquire their best performance for bulk sensing applications. The experimental results show that the PWR sensor has a refractive index resolution of 5 × 10(-7) RIU which is 6 times smaller than that of the optimized SPR sensor. The TE polarization in the PWR sensor has a resolution of 1.4 × 10(-6) RIU which is smaller than the SPR sensor. The polarization diversity in the PWR sensor is another advantage which can be used to improve the measurement reliability.