a well built aluminium rack is better than a big heavy steel one, if you opt for steel get a full gutter support type as it will spead the weight better as suggested by Threedogs but you have to be carefull with weight, if your running steel bar, winch, steel rims, steel rack, draws etc etc you run the risk of to much weight on the vehicle all the time, the weight a vehicle is allowed to carry is governed by how many seats in the vehicle, the more seats the more weight you can carry, people often make the mistake of removing the rear seats (dickie seats) to make room for drawers, once removed you have removed your option to carry more weight legally, it is a risk most people are happy to make but you should also know the consequences of overloading a vehicle if there is a accident, I am a firm believer in quality aluminium roof racks, no need to be too top heavy, steel isnt always better