Both sitemaps are important for any website. HTML sitemap is used by humans whereas XML sitemap is used by search engine. XML sitemap is the best option to make your pages crawled.
Xml Sitemap is for Google Bot. XML Sitemaps is an easy way for you to submit all your URLs to the Google index and get detailed reports about the visibility of your pages on Google. With Google Sitemaps you can automatically keep us informed of all your web pages, and when you make changes to these pages to help improve your coverage in the Google crawl. HTML Sitemap is for human. HTML sitemap is one of the most important tactics you can use to distribute your link juice efficiently within your site. It is a bulleted outline text version of the site navigation. The anchor text displayed in the outline is linked to the page it references. Site visitors can go to the Sitemap to locate a topic they are unable to find by searching the site or navigating through the site menus. Sitemap can also be created in XML format and submitted to search engines so they can crawl the website in a more effective manner.
Both are different and useful. Try to create both in your website. HTML sitemap is user & search engine friendly and XML sitemap is only search engine friendly.
Here I would like to say in one line , XML for search engine boot, where as HTML beings for visitors.
HTML SITEMAP? HTML sitemap is used to list all hyperlinks of different sections and pages of your blog/website. These hyperlinks are normally listed hierarchically and they may provide description for each link. It is no doubt that adding a HTML sitemap to your blog/website will help your visitors navigate and find information easily. So HTML sitemap is primarily created for humans. XML SITEMAP? XML SITEMAP allows webmasters to inform search engines about URLs in your blog/website for easy indexing. XML sitemap is created for search engines but not for humans. Submitting a XML sitemap to search engines such as Google, Yahoo, and MSN will not only help your blog/website being indexing quickly and efficiently but also increase your blog/website’s visibilities in search engines as well.
HTML sitemap is for humans to read it and watch it & XML sitemap is for Search Engines to crawl the Site.
Xml sitemap easily crawl by search engine is best for newly created pages that quickly crawl and html sitemap is basically for user which easily searchable and manage sites.