Hi Anil, both are great SEO tools I would say because I’ve been using both of them for a long time now. SEMrush offers even more incredible features and their databases are even bigger and regularly get updated when compared to Ahrefs. But as you said, Ahrefs is equally good and I really like their keyword analysis data to be precise when compared to any other tool.
As of September 2014, YouTube's own keyword tool stopped working. It was moved over to Display Planner's AdWords video keyword suggestions. To use it, you need to have an Google Ads account. Just like the non-existent YouTube keyword tool, it was created to facilitate paid video and ads promotion. Which is why keywords that you will find there might not be closely related to the topic that you want to cover.
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.