e commerce - What is the best eCommerce add-to-cart flow?

I'm working on an eCommerce website. I found two predominant approaches as to what happens when buyers click the add-to-cart button:

1. Send them to their cart where the main action button is "Checkout" and a well-less notable button is "Continue Shopping" (where this button sends you is a whole other debate).


2. Give buyers a well-noticed notification that the item was added to the cart and leave them on the same page. Approach 2.a. is to use a popup product page so when buyers click the add-to-cart button they see the notification and then they are back at the store section where they selected the product.

I strongly support approach #2.a. but since almost all eCommerce websites go with approach #1 - I want to make sure I'm not missing anything. Following this analogy, approach #1 is like you go into a supermarket, push your cart to the milk section, pick up a milk bottle and put it in your cart. Then you and your cart are magically lifted up and placed in front of the cashier.

Assume I have unlimited resources - what is the best add-to-cart approach?