If you notice your site is taking a long time to load, then you should first use PageSpeed Insights to see what can quickly be optimized (also check your file sizes, hosting server, NGINX and other common sources of slow speed, too.) And, if you've notice gradually fewer Organic Search visits, PageSpeed Insights might be able to help. As Google is reducing the prevalence of slow sites, you could be losing traffic. Speed up your page load times by finding what is blocking renders, slowing down contentful paints, and other critical page speed signals.
If you're just getting started and want something simple to get a boost on your SEO, then it is a good place to start. It takes you through the initial steps and show you where you can improve. The paid versions are still pretty cheap compared to the competitors, but some of the others have more features and functional areas. However, bear in mind that the main reason this product exists is to provide leads for NPDigital marketing agency, so you'll get a fair amount of push in that direction.
Some of the tool's features, including backlink tracking and competition analysis, were either lacking or more appropriate for the top-performing websites that already had a lot of traffic. So they should improve in this segment
It's really easy to use. The interface is nice and tidy, and the learning curve is low. So it's a tool that's accessible for everyone. If not, there are plenty of guides in the tool itself or on the website. You can easily make lists and export data for use or to share, connect Google Drive, and go work with a team.
They have a lot of information on their website, and also training and contact options in the tool. So you can learn on the go while trying the tool. And if you are stuck, support reacts really fast--sometimes the same day, sometimes the next day due to time zones. Payment is easy and easy to cancel.
I think GTmetrix has some feedback that PageSpeed doesn't provide, but Google's tool is easier overall and has a better user experience; also offers compressed images, CSS, and javascript files if that's the case. Also, Google has extensive documentation to help you better understand what can be done to improve your grade.
We use each SEO research platform for different purposes. I believe they complement each other. Ubersuggest strengths, according to my experience, are related to content ideas, comprehensive keyword research to determine competitors' backlinks, and difficulty in achieving the desired results for any given SEO campaign. The Ubersuggest topic ideas tool gives different insights and benchmarks in relation to other similar platforms that fit our marketing needs.