I had the same question last year. After testing the Semrush and the Ahrefs, I decided with Semrush, it looks like more advanced and having a lot of tools ( which I haven't used yet :)
What I liked with Ahrefs, finding good performing contents is much easier, you can find good content and inspire from them.
I tried Semrush before, they have very detailed information that you can use to analyse your website from every different aspect. However, Ahrefs is good enough for you and me - people who just started SEO.
I'm using SEMrush right now, but I have used Ahrefs before which is more user-friendly in my opinion and experience.
Since you're looking for the first SEO tool, then Keywords Everywhere is also a good choice
Simply before deciding, consider digging and reading into some of the best Free resources, almost a dozen through the following link and throughout the SEO educational web pages for further information... :)
All the best,
I don’t use any of these, I prefer to kill two birds with one stone, but doing to soovle.com input any related keywords if present by clicking that long tailed and viewing then scroll to the bottom as google provides possible suitable alternatives. 2 birds with 1 stone
I've used both SEM Rush and AH Refs I think both are great tools, I personally prefer the UX/UI of AH refs but that's personal. I think when you're starting out with SEO sometimes advanced tools give you more info and tools then are helpful. You can also check out something like Mangools which I think is like $30 a month which I've heard good things about.
Honestly, the best instant thing to help SEO is switching over to cloud hosting like AWS or Google cloud, there's a great case study on the effect of better site performance on ranking. https://www.rebootonline.com/blo...
For overall performance, you can use something like GT Metrix to check how your site currently performs and what to fix. This will help a ton with technical SEO, but it's still a pain and takes a ton of time, most site builders are just slow and bloated.
The biggest place I see people missing out on is distribution. After publishing content get it out there. Quora and Twitter are great ways to do this, answering relevant questions and linking to your blog posts as long as it's useful.
Lastly a shameless plug, I co-founded Wizrd.org which is a blogging platform that provides a blog optimized for performance and technical SEO and focused on being super simple and easy to use. Depending on what functionality you want to use it might be perfect to get you started.