Best fast and responsive theme for adaption?

Hey everyone. I come from drupal where I used to write and design my own templates based on a good responsive template. I would just adapt what is necessary, colors, page layouts and so on but e. g. the navigation would more or less stay the same. So my decision to choose a template is not primary how it looks (because I can change that) but rather how well it is coded/built (responsive and fast e. g. without heavy javascript) since I can't start from scratch. I will adapt the template for a niche news site. What are some templates that are best practices and you would recommend? Thank you very much in advance.