After eating dinner, washing the dishes, playing around with it and reading the comments in views-view-fields.html.twig located in core\modules\views\templates
/**
* @file
* Theme override to display all the fields in a row.
*
* Available variables:
* - view: The view in use.
* - fields: A list of fields, each one contains:
* - content: The output of the field.
* - raw: The raw data for the field, if it exists. This is NOT output safe.
* - class: The safe class ID to use.
* - handler: The Views field handler controlling this field.
* - inline: Whether or not the field should be inline.
* - wrapper_element: An HTML element for a wrapper.
* - wrapper_attributes: List of attributes for wrapper element.
* - separator: An optional separator that may appear before a field.
* - label: The field's label text.
* - label_element: An HTML element for a label wrapper.
* - label_attributes: List of attributes for label wrapper.
* - label_suffix: Colon after the label.
* - element_type: An HTML element for the field content.
* - element_attributes: List of attributes for HTML element for field content.
* - has_label_colon: A boolean indicating whether to display a colon after
* the label.
* - element_type: An HTML element for the field content.
* - element_attributes: List of attributes for HTML element for field content.
* - row: The raw result from the query, with all data it fetched.
*
* @see template_preprocess_views_view_fields()
*/
{{ fields.title.content }}
worked for me. In hindsight it's very similar to the D7 code, duh, lol.
For other fields:
{{ fields.machine_name.content }}
What's the machine name? You can find them under the Machine Name column in the Manage Fields of your content type or block.