Stripe is a method of payment with one of the fastest processing speeds. Their payment system is done on the platform and lets you stay on the checkout page during payment instead of redirecting you to another page.
WooCommerce, one of the most extensible WordPress plugins, enables eCommerce capabilities to otherwise lead-generation or informational-based sites. Currently, it has one of the biggest market percentages of all online shopping sites.
I recently came across a situation where a Client needed over 100 variations with certain variations only being specific to a particular attribute. This means I needed to create the variations dynamically and then individually delete each variation that was not relevant to the particular attribute.