So far I have bought three codes and I plan to buy more.

I have many other SEO tools which also provide me with SEO audits and analysis.
But what I like about Siteguru over the others is

1. It's very well laid out. Having all the data in the world is pointless if it is hard to understand. I have several SEO tools I never use for exactly this reason.
Siteguru present it all very well indeed.
2. It found a few things missed by my other audit programs - which surprised me a lot
3. The insights section is worth it's weight in Gold. I know the data is available in the Google Search Console, but really this is how Google should be presenting that data. Good job Siteguru
Again this comes down to showing what is important in a way that can be understood. (Which is not Google's strong point!)

The only downside I have is the number of sites you can monitor is limited to one per code. And maxes out at ten sites/codes. If you only mange a few sites this is fine, but for an SEO agency this is nowhere near enough.
An agency plant would be welcomed.