They really shine in scorched earth, as they are everywhere. Its fairly easy to tame a legion of them with a few boomerangs. Early on this can provide you with a solid defense. And once you can make a saddle you can get to mining huge amounts of metal, obsidian, and crystal from the mountains. Have other dinos like kentros or morella to carry the obsidian and crystal as the ankys don't have reduced weight on those, they should be fine carrying stacks of metal. Weirdly they seem to have lower base health than doedicurus, but stronger attacks. Also they can harvest huge amounts of flint from regular rocks to make sparkpowder.
The Ankylosaurus is, in my opinion, one of the best dinos to tame as a low level. Not only is it the best dino to gether metal, it is also a great taming mount, because it can collect berries and can kill little things like Raptors easy. This will be one of your most used dinos when you get into the higher levels and taming an Anky as soon as you can make the saddle (lvl 40) is highly recommended.
With the recent update Ankylo can hold four times the metal because it weighs less as long as it's in ankylo 's inventory. So 100 metal will weigh 25lbs instead of 100. Also tamed Anky will have more speed than usual. Happy farming ^__^ -Geo