The individuals will benefit the most from the GDPR. You have more rights now compared to before the GDPR. It is also much easier to exercise them by contacting the company or the supervisory authority in your country. Even if the company is from another EU country, your local authority will forward your complaint.
You have the rights to be forgotten and to deny consent for the use of data. At any point, you can ask what is being done to your data and demand a copy of it. Generally, nobody can do anything with your personal data unless you clearly consent – such as when marking a check-box online or providing a physical signature.
There are a few more rights you can exercise. Find them here.