These are top and recommended Reward point extension for Magento 1 & 2.

1) Reward Points by Landofcoder

With Reward Points extension, you can easily attract customers to your store. It accumulates when a customer buys, shares a product or reviews about a store. In addition, customers can use this points to pay as well as participate in attractive promotions. From that, it helps stores improve sales, attract new customers, and retain old customers.

Link: https://landofcoder.com/magento-2-reward-points.html

2) Reward Points by Mageplaza

The Magento 2 Reward Points by Mageplaza allows customers to earn unlimited points through the actions of customers such as buying products, sharing products through social networks, etc. Besides that, customers can use points as a payment method. This not only helps attract new customers but also retain loyal customers for your online store.

Link: https://www.mageplaza.com/magento-2-reward-points-extension/

3) Reward Points by Aheadworks

To give customers a great shopping experience from the store as well as to give them exciting promotions, Magento 2 Reward Points is a perfect tool to do this. You will no longer worry about the quality of the store's service, this extension will help you remove all other concerns and satisfy the difficult customers.

Link: https://ecommerce.aheadworks.com/magento-2-extensions/points-and-rewards

Reward Points by Mirasvit is also very popular and powerful extension for magento 2: https://mirasvit.com/magento-2-extensions/reward-points-referral-program.html