I am using ahrefs, spyfu, semrush for competitor's analysis.

SEMrush allows you to get insights into your competitors’ strategies in display advertising, organic and paid search, and link building. You can easily analyze which are the best performing keywords of your competitors. It also enables you to analyze competitors display ads and get the right keywords for both your SEO and PPC campaigns.

Semrush
Backlinkwatch
Ahref
Spyfu

Ahref and semrush is the best tool there are also website available on Internet where you can use it.