There possibly are some that are EQ but the vast majority are Alt/Az with LARGE field derotators. One of the other big reasons for having them as an Alt/Az design is that some on the Keck system have Nasmyth systems so that there are instruments at "normal" RC position and then a few more mounted to the sides. I believe Keck 4 has this.
PlaneWave make a couple of decent Alt/Az designs as does
ASA Astrosysteme GmbH.