There are two popular WordPress plugins which generates XML sitemap.
Yoast SEO and Google XML sitemap
Both have almost equal reputation, ratings and installed in more than one million sites.
I confused which to choose for my website. Please show the light on me. Thanks.

Previously I have used the Google XML sitemap for more then 3 years.
Once Yoast SEO sitemap came into picture, i just wanted to give a try. After switched to Yoast SEO sitemap, my post got indexed in google within a day.
Its really working wonderful. Now currently I am using Yoast SEO sitemap only.
The only disadvantage is, its not a standalone plugin. You need to use along with Yoast SEO wordpress plugin.

Both will do the same job.The only difference is Google XML sitemap will have lot of options to customize your website's sitemap.
Yoast SEO will have required options and do its job perfectly.

The choice is yours. Since both doing the same job, you can choose whatever you want.