I haven’t personally used Crush but I did run tests with Zeely and Adamigo over a few months.
My honest takeaway after all of it is that the platform you choose is probably the least important variable in the equation. What actually determines whether paid ads work is how well your website converts. You can connect the best ad tool on the market but if your landing page is losing people before checkout you are just paying to send traffic to a leaking funnel.
In terms of the tools I tested, I would not go back to either of them personally. But results vary and your situation might be different.
If I were starting over I would fix the website first. Get your add to cart rate above 5%, reduce checkout friction, make sure your value proposition is clear within the first three seconds of landing. Once that is working, almost any half decent ad platform will produce results.