My kids use CTC Math and like it, but Pat (the creator) has said that past sixth grade, CTC Math is more of a supplement than a curriculum. It's helped my kids a lot, they used it over the summer and are now getting A's and B's in math when they used to get B's, C's and the occasional D. :-! They are in 1st, 2nd and 4th grade. They still have trouble understanding the lessons every now and then, so sometimes I have to explain it them, or find an appropriate YouTube video.
Khan Academy was useless to us. It didn't help them at all.
HELP Math is really good, it's for older students (grades 4-8, I think) and you can also look into Gizmos... I think it's Learning Gizmos. It's made by the same people who created Reflex Math.