The plugin’s initial setup has all the possible form plugins set to “true”. This likely means that some code is being executed for each of them every time the plugin runs, which is wasteful. It also requires manual action to change the settings.
A better way would be to use is_plugin_active() to detect each of the form plugins automatically. This can be done on plugin activation to set the flags (faster), or it can be done every time the plugin runs (always up to date).
Export/import of settings
For people who manage multiple sites, it will also be good to have a settings export/import feature, so that configuration can be quickly copied from one site to another to save time.
Cosmetics
I’d move the “Save Changes” button to the bottom of the page.
Better handling of form plugin detection
The plugin’s initial setup has all the possible form plugins set to “true”. This likely means that some code is being executed for each of them every time the plugin runs, which is wasteful. It also requires manual action to change the settings.
A better way would be to use is_plugin_active() to detect each of the form plugins automatically. This can be done on plugin activation to set the flags (faster), or it can be done every time the plugin runs (always up to date).
Export/import of settings
For people who manage multiple sites, it will also be good to have a settings export/import feature, so that configuration can be quickly copied from one site to another to save time.
Cosmetics
I’d move the “Save Changes” button to the bottom of the page.