What SEO plugin do you recommend?

WPL is SEO friendly itself and has many features for improving SEO on the WPL views so you don't need to install any plugins for improving WPL SEO but you're free to install an SEO plugin for other sections of your website like blog, pages, etc.

BTW, we don't recommend any plugin, you can use the one that you like. There are many popular WordPress SEO plugins in the WordPress community and most of them should be compatible with WPL.