I’ve used lots of different tools over the years and I would have to say that I’ve been overly impressed with SEMrush. The tools are easy to use and provide great data to help me make SEO suggestions for both large and small businesses.
If you are serious about taking your SEO to the next level (and who isn’t), you should do a test with SEMrush.com. You won’t be disappointed. BTW, this is an affiliate link. I endorse them because they are simply a great tool.