I love TT for my DS with ADHD. He does so well with it!
It is about 1/2 a year behind most PS math but since you can work at your own pace, they easily get ahead.
I also love MUS. It teaches things a bit differently than traditional American schools but my oldest was pulled from PS after 3rd and transitioned into it well. We had to review sometimes but he picked it up fast. I LOVE LOVE LOVE it for the k-4th mastery of the basics and learning the facts.