I have traveled in both the trains very often. If you get the tickets in 12163 Dadar-Chennai Egmore exp., take that, because it is very fast and well maintained. At the worst case you can go Kanniyakumari exp which is very worst maintained, not good food, too much slow etc., Remember 12163 will not go to Tirupati station, only upto Renigunta from where you get good connectivity to Tirupati.