Hi Siva,
In general, RZ format is preferable for bit rates higher than 10 Gb/s due to pulse broadening issues. However, since you are working with the bit rate of 10 Gb/s and using appropriate dispersion compensation techniques, NRZ bit rate will be more beneficial due to increasing pulse energy (which is higher with the respect to noise in this case!). According to my experience with the dispersion compensation, the choice of particular compensation technique depends on your particular scheme design…