SEMrush is hands down the best tool for keyword research. I love that you can do competitor analysis and find the keywords people are searching to go to your competitor's site. You can add all your projects in one big dashboard and see a quick overview of your keyword rankings (I do this every other day to check if my sites were penalized/keywords dropped). The reporting feature is also a great alternative to Google Analytics and we send automated reports to our clients.
SEMrush is one of the most comprehensive SEO and SEM tools out there. However, it is not a tool for the budding entrepreneur who is still getting to grips with laying out their website or has no idea what a landing page is. It is a powerful tool that requires a degree of experience. Some tools are obviously more complex than others. Then there are tools that some businesses may never use. Though in the grand scheme of things the goal of every feature ranging from its backlinks monitoring to keyword research, competitor analysis is to give you a leg up on the competition.
Another feature of Ahrefs that could potentially help you take your campaign to even better heights is their content gap feature. It gives you the option to check which keywords your competitors are ranking for so you can stay one step ahead at all times. Basically speaking, Ahrefs gives SEOs the ability to overtake their competitors through knowing which keywords to target and focus on.