SEO Powersuite is a bit of a different product. It is not a cloud-based service, but a desktop application, or even a set of desktop applications. Actually the suite contains 4 programs. Combined, they basically provide you with all that you need for your SEO campaigns. It depends whether you like to work with a desktop appilcation or not. If this suits you, you get a full-powered set of software for a one-off fee, without the need for recurring fees, and unlimited number of websites to track. This makes it stand next to Market Samurai and WebCEO though they all have their stronger and weaker points.
SEO Powersuite offers a limited edition that allows you to try out most features. It has limitations as to how many items can be checked /investigated and it doesn't allow you to store the project information, for this you need to buy the full version of either $299 or $699 (the latter for reporting options). Also it is possible to buy the products separate from eachother. So, let's simply discuss the 4 different applications separately, they work fully independant of eachother:
The name Rank Tracker may be a bit confusing, one of it's functions is indeed tracking rankings in search engines over time, where it allows scheduling of the tracking in the paid versions of the tool. Also however, it is aimed at keyword research. It features keyword suggestions, competing sites, AdWords integration. Keyword suggestions can be created in numerous ways, with also the possibility to emulate keyword suggestion mechanisms from SEMRush.
The website auditor is more a tool that could be usefull in the free version, especially if it is a one-time SEO audit for one of your Joomla sites. It checks various ranking metrics, available in a global overview for all your pages, or specific to one paricular page. Like with the other applications, you can generate reports that you can email to clients from with the tool:
SEO Spyglass is a tool for checking out competitors in the search engines.
This tool can check out a lot of information, and look out for potential link-partners, based on either keywords or simply by checking out competing URLs. Also you can configure a default link-request form to send to potential link-partners.
You can check out further information and prices on the Link-assistant.com website.