Is ITF legitimate, or should it be avoided like WTF and ATA?

ITF Taekwondo was first started by Choi Hong Hi. Choi trained in Shotokan Karate for a few years and then blended that with Taekkyeon to form Taekwondo. ITF Taekwondo was founded first, then came WTF which was founded in 1973, due to political issues.

A style is only as good as it being taught. If the place offers Cardio Kickboxing, it is probably doing that for money reasons; HOWEVER, most schools have some money making part, even if the schools are legitimate. They have to make money or they would go out of business. Just because it offers that class does not mean it is a Mcdojo. Go to the school and visit and take a trial class to see what then school is like.

Personally I would avoid TKD all together. I think the original TKD is probably good and can be good. But in today's world TKD is the representation of McDojo's. Weather people like to admit it or not there are an endless amount of McDojos in TKD. Are there good schools out there? Probably yes. But finding them is at this point literally like looking for a needle in haystack.

Cardio kickboxing has very little to do with kickboxing. It's cardio. It's for people who want to get some exercize. It's not a McDojo. They say it in their name that they are meant just for exercizing. It's not martial arts or kickboxing.

I have seen 2 true TKD schools in my area. The Fed/Assoc. does not matter, the teacher does. And, fast or slow does not matter. One trained slower, another faster. I know people from both schools and they have great technique, speed, power, ect. (The slower school speeds things up occasionally to further refine technique.) Lets just say both places produce great strikers ;)

If you can find a good TKD school focused on technique, power, breathing, and other intricacies, then join for sure!

Cardio Kickboxing isn't even close to fighting. Just burning fat.

There isn't much legit TKD places unless you live in Asia(Vietnam, Korea, possibly China)