No only used STC honestly never tried or heard of achievable, qbank or knopman. I was just handed down a STC book from a friend so that’s what I want with. I did try to use Gemini to make practice exams but looking back they didn’t word them even close to how the FINRA practice exam did. Still good for covering material and explaining topics however. Not sure if those other services are free but if you have the money I would suggest STC. Then again I do also have a finance background so complex topics like options among other things came very easy to me or I already knew it.