ResumaidPro is a flexible AI tool that lets you customize a resume, cover letter and email interface. It then can automatically customize the documents to match a job description, so it's a good option if you're applying to lots of jobs.
Another good option is Kickresume. It uses AI tools like OpenAI's GPT-4 to write human-sounding text for resumes and cover letters. It's got more than 40 ATS-friendly templates and a large library of examples you can draw from, so your applications should look good.
If you want something more integrated, WonsultingAI has a variety of AI tools, including ResumAI for resumes, CoverLetterAI for cover letters and InterviewAI for mock interviews. It also has tools for building your network and tracking your job applications, so it's a good option if you want to use it as a foundation for a serious job search.