They each have their benefits. I like Yoast because it breaks up pages, posts, and categories and it notes how many images are on the page which can be helpful for getting indexed in Google image search. Yoast DOES NOT auto-submit to webmaster tools (to the best of my knowledge), so you'll want to make sure you manually submit all 4 sitemaps (index, page, post, category).
Google Sitemaps is a little less involved. It automatically submits to Google which is great if you are in a hurry and it isn't critical to squeeze the most out of the site.
For sites that I really care about, I use Yoast, but for bulk sites, Google Sitemaps is my choice.