I don't believe one device is necessarily "better" than another. When I use a softer brace, the Storm Xtra Roll is my favorite. After trying at least a dozen braces (Including a few of the Robbys), I liked the feel of the Xtra Roll best. Mostly because it achieves a good balance of adequate support without being overly restrictive. But it's all about personal preference. I know others who have tried the Xtra Roll, and hated it.
The Mongoose Equalizer is also nice. It's very comfortable, but a little less restrictive (and a little less supportive) than the Xtra Roll. It's a matter of what you need.