Exit Subscribe Pop UP

Having an offer for site visitors as they exit your site has become the rage... and has proven high value features you should consider adding to your site. Have tried the Bootstrap Modal add on and found it lacking in automation, just couldn't get it to work with plugins like YOAST SEO and other issues of custom code... Started looking for other plugins that other "free" popup forms to place a "subscribe" offer. Started with Exit Popup but found it didn't work very well in all environments and it added extra width and height to a short code put into their popup using FF forms. And didn't work on Mobile phone [actually couldn't find any that did]? Now using/testing wBounce and find the interface much cleaner and with more coding options. Anyone else have ideas on the use of these "get people to subscribe" tools?