Which paid tools are the best?

I run a website for my own company and do some SEO myself but hasnt significantly worked. It is trekking website and niche is travel niche. I use rankmath plugin which is free for basic seo . I am struggling with backlink buiilding for now. But my major question today is:

Which paid tools are the best ? If i want to spend some money I want them to be on the best tools