It depends on the size of your operation, but I think you could get just as much value out of the Mangools Suite. This is the group in charge of KWFinder. But you can also take advantage of their SERP watcher and LinkMiner, and SiteProfiler features since you have an established business. They aren't quite as powerful as Ahrefs, but they get you 90% of the way for about 50% of the cost.
The other star feature of the Domain Vs. Domain tool is it provides you with a detailed report on the competitors’ domains. You can see all the common keywords their domains are associated with and compare their website’s position for each keyword to your own. This allows you to get some insight into what is working for the competition and mimic their success by optimizing your ad strategy and content marketing.