Panera just acquired one of its biggest competitors — here's why it won the comfort-food battle

• Panera announced Wednesday that it would be acquiring Au Bon Pain.
• The two cafe chains serve similar menus of soups, salads, and sandwiches.
• Before the acquisition was announced, we pitted the two former rivals against each other and found we preferred Panera. 

Au Bon Pain and Panera, star-crossed cafe chains, are set to be reunited at last.

Panera Bread announced on Wednesday that it had entered into a definitive agreement to acquire Au Bon Pain Holding Co. Inc. Both cafe restaurants were once together under one parent company back in the '80s and '90s, and with this acquisition, the two will be reunited once again. 

The Au Bon Pain transaction is expected to close during the fourth quarter, and terms of the deal were not disclosed. JAB Holdings paid roughly $7.5 billion to buy Panera earlier this year. 

These chains serve all the classics: steaming soups, fresh salads, hot paninis, and more.

But a question arises: Whose food is the better lunch choice?

Panera Bread, with over 1,800 locations, and Au Bon Pain, which has roughly 300 cafes worldwide, serve very similar menus.

Before the acquisition was announced, we put Panera Bread and Au Bon Pain in an extensive head-to-head test to find out who serves the better lunch.

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The two fast-casual-cafe chains offer very similar menus, so we chose a handful of items we think are classic and hearty cafe fare.

First up: sandwiches. Here are both chains' takes on the hot chicken and mozzarella panini.

Au Bon Pain's Chicken Pomodoro sandwich — with chicken, mozzarella, asiago, tomato spread, and roasted tomatoes — was underwhelming. Despite being made fresh to order, it tastes like prepackaged chicken parm. The ciabatta bread is spongy, and the spreads were lacking flavor.