I do use them, but the Turbotax one has a nice feature on the final screen -- a slider to see the effect of extra withholding amount. It is the most intuitive among the three.
I get it that I can just use the IRS tool, but that's not my question. If Turbotax doesn't want to offer this tool anymore, why still showing it? An outdated and inaccurate tool on your website isn't going to boost Turbotax users' confidence in your product.
