We present results of an optical spectroscopic survey using SALT and the Nordic Optical Telescope to build a Wide-field Infrared Survey Explorer mid-infrared color-based, dust-unbiased sample of powerful radio-bright (>200mJy at 1.4GHz) active galactic nuclei (AGN) for the MeerKAT Absorption Line Survey (MALS). Our sample has 250 AGN (median z=1.8) showing emission lines, 26 with no emission lines, and 27 without optical counterparts. Overall, our sample is fainter ({Delta}i=0.6mag) and redder ({Delta}(g-i)=0.2mag) than radio-selected quasars, and representative of fainter quasar population detected in optical surveys. About 20% of the sources are narrow-line AGN (NLAGN)-65% of these, at z<0.5 are galaxies without strong nuclear emission, and 10% at z>1.9, have emission line ratios similar to radio galaxies. The farthest NLAGN in our sample is M1513-2524 (z_em_=3.132), and the largest radio source (size ~330kpc) is M0909-3133 (z_em_=0.884). We discuss in detail 110 AGN at 1.9<z<3.5. Despite representing the radio loudest quasars (median R=3685), their Eddington ratios are similar to the Sloan Digital Sky Survey quasars having lower R. We detect four CIV broad-absorption line (BAL) QSOs, all among AGN with least R, and highest black hole masses and Eddington ratios. The BAL detection rate (4_-2_^+3^%) is consistent with that seen in extremely powerful (L_1.4GHz_>10^25^W/Hz) quasars. Using optical light curves, radio polarization, and {gamma}-ray detections, we identify seven high-probability BL Lacertae objects. We also summarize the full MALS footprint to search for HI 21cm and OH 18cm lines at z<2.