With my 2 years of experience, I think I am ready to review best keyword research tools.
SEMRush (Paid) : - If you are seriously concerned about SEO and want to rank then you must give this tool a try. Its charges are way more than normal but it is worth every single penny. It gives you good results about keywords, trends, competitions, backlinks, etc. To increase number of users SEMRush also introduced 30 days free trial period whereas you will have to pay for regular use.
Google Keyword Planner (Free) : - It is good as well compared to other SEO tools available. As it is directly from Google, it regularly updates its database. After SEMRush I would suggest you to for Google Keyword Planner. Same as SEMRush you will get keywords details, trends, etc. but for backlinks and competitor research you will need to rely on other services.
I used many SEO tools but I can say that none of them works as good as SEMRush and Google Keyword Planner.
I am currently pursuing High School and planning to pursue career in Computer. Currently, I work on one of my blog - JTech Articles.