Binary mass ratio, q, of merging MBHBs detected by LISA with S/N > 7. Each panel shows merged binaries with different total mass (M_Bin). Blue histograms represent the predictions of the Fiducial model and orange histograms represent those of the Off-center model. Horizontal dashed lines highlight the median value of the distribution. The results were produced using L-GalaxiesBH applied to the Millennium-II simulation.