Formative is one of my favorite tools I've ever shared for assessing students. The feature that makes Formative stand above others is the ability to award points and give feedback in real time, which works well if you are gamifying your instruction. There is also the ability to view students while they are being assessed.
Watch this Chat with Deb video and see all the of features of Formative.
If you decide to use Formative, let me know how it goes. I look forward to hearing from you.