Not sure about the sizing on the Antares. It's hard to go wrong with a down bag from a good brand though if it fits. Check the return policy. If it's good, then try the bag for size.
If you are having trouble with the big bags being big enough, then you might look at a down quilt like Jacks R Better. Depending on fill and quilt size, you should be in the two to three hundred dollar range.
