Which SEO tool should a small business start with?
Google Search Console, and it is free. It shows the queries you already appear for, which pages Google has indexed, and what it could not crawl — none of which a third-party tool can tell you as accurately.
Are paid tools worth it?
Once you have more pages than you can check by hand, or you need competitor data. Below that they mostly report what Search Console already gives you.
Does ZENVIQ run these tools?
No. These are other companies' products, listed because they are the ones worth knowing about. The tools ZENVIQ builds and hosts are marked separately on the tools page.