Can’t say that I’ve tried a lot of them but I’ve tried a few (mostly the popular ones). Currently, Merkeleon is the best cryptocurrency exchange software for me. You can create your own trading platform. The interface is pretty intuitive (which for me is really nice, cause sometimes I’m having troubles figuring out stuff like that). A lot of payment options, the software supports the top payment systems and you can make withdrawals using bank cards if you need.
As far as security goes, they provide anti-fraud solutions. So far my experience has been nothing but positive.