Pros: I use the free version for my small e-commerce website. I have been able to link up my social media accounts so I can keep track of how they are doing and how much more (or less) engagement they each get week-on-week/ month-on-month. I've input my competitors so I can see how they are doing when comparing to mine (it's nice to know if my rankings have reduced and others have, it's perhaps a seasonality thing) SEMrush gives you masses of tips to help you improve your website, really drilled down into tips per page. My account is limited as it's the free one so I get updates monthly as to how my page tips are doing (such as I need to add ALT tags) but I actually like monthly reviews as it gives me plenty of time to get cracking and make a dint in my to-do list.
Pros: I love how simple SEMRush is to use and how intuitive their UX is. I've used their topic research tool for clients and it has helped inform their entire content marketing strategy, from the calendar itself to the amount of paid/organic attention we give each piece of content. Their tool is always fast, loads quickly and is easy for novices to understand.
Get Product Feed Insights: While Google AdWords may use keywords to decide if an ad should be shown product listing ads tend to manipulate the product feeds. So, the competition’s PLA feed is a secret, but that’s where this feature comes in. The Position Report generated shows keywords that are signaling their listing to show ads, their PLA’s ranking in search results, the PLAs that are popping up for each keyword, and a promoted product’s price and title amongst a few other things.
Competitor Backlink Audit: Analyze the link profile of your competitors and look for opportunities that can help improve your own link building and search performance. Whenever you perform a competitor backlink check or audit, you must also check the inbound links that are pointing to top ranking pages so you wouldn’t miss out on important link opportunities.

The Intersecting Link Opportunity report we love could offer an automatic version that takes into account the top 20 listings for a given keyword phrase, saving the researcher copy/paste time and having to run multiple requests. Their Most Popular Content list is definitely helpful, but doesn't give us the semantic relevancy we get from the intersecting report.

SEMRush is one of the best solutions I have found for discovering site errors, getting a great explanation on how to fix it, and even posting for social media. It covers end to end so many of the varied areas of SEO, that it's become an invaluable part of my business. My favorite has been utilizing the ranking tools to see how we compare against competitors, and also tips on getting featured snippets (which we achieved for one client this year!)
Ahrefs is incredibly comprehensive and straight forward. From keyword discovery to site audits I use ahrefs for all my SEO needs. It's the first SEO program I was introduced to when starting me SEM management career and has proven to be the best time and time again. I've used their competitors liker moz, SEM rush, and a couple other services- none of which have come close to stacking up.
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