What is the best GTM plugin to use with Wordpress and Stape?
There is a Stape plugin for WP: GTM Server Side – WordPress plugin | WordPress.org
But you can use any suitable one for you. For example GTM4WP is often used.
Can anyone here explain pros and cons of this choice? (Assuming woocommerce is not installed?)
Assuming there’s no Woocommerce installed the difference is negligible. With no WooCommerce both plugins would pretty much just let you embed GTM.