my both girls had heely's for a while. While they are a bit more expensive, they are heads and sholder above the competition.
This time we went with the X2 (double roller) heely's. The girls seem to like it at least as much as the regular one-roller heelys. Plus there was the "whoa" factor in the school as few kids yet've seen double rollers. However, even the single ones were perfectly great.
Just a suggestion about the size - buy at least a size up, as heely's is fitting exactly, so since my kids grow, they can outgrow their own size pretty quickly. Yet, due to Heely's quality, their shoes are still sparkly and perfect. A size up means the girls get to ride the same heely's for at least 2 years.
Alex