There's many dyes that you can use for tie dyeing and your selection will depend in a number of factors, such as the nature of your fiber.
For instance, if you are dyeing wool or if you're dyeing silk or cotton. It will it also depend on the nature of your work. For instance, if you're just trying to have fun with your kids or if you're trying to dye something that you want to wear and wash a lot of times or even if you're dyeing something that you plant to sell.
There's many different dyes. There's fiber reactive dyes which are the ones that I prefer and that I will be using for these tutorials and they're pretty much focused for cotton fibers. And then there's acid dyes that are more suitable for silk fibers. And then there's Rit dyes that everyone knows and they're available at any supermarket and they're really cheap and they're easy to use. And finally, you can even get color out of natural dyes. For instance, you can extract awesome yellows out of onion skins and you can get really nice pinks from avocado pits and even berries can be used to dye fabric.
And these are just a couple of examples of dyes that you can use for tie dyeing.