Neither domain name option is a very good idea. I'll explain why in a second, but first I'll answer your actual question.

Although there might arguably be some slight advantage in having an exact-match domain of the form Name.TLD as opposed to a domain with additional keywords alongside the name, that advantage is probably negligible. Google algorithm updates, as I understand them, withhold that exact-match-domain advantage until a website has many other reinforcing signals of authority. (Their goal has been to downgrade spammy, low-quality websites.)

Whichever domain version you might choose, Google will find the brand name CUJO mentioned all over your actual website and in the referring links. Those signals will be plenty for search engines to pick up on and hence plenty for SEO, and I'd expect them to overshadow the tiny difference between the 2 domains.

Your choice shouldn't be based on SEO. Stop trying to please search engines, and start paying attention to your actual human audience. Really, your decision ought to be made based on the memorability and first impression of the domains. Is the extra keyword in .COM better than a name without that extra keyword in .IO? For humans, that is.

Either way, you'll run into competition from CUJO.com. And that's a potential problem.

Another problem would be pronunciation ambiguity. Spanish and English speakers will see the name very differently, based on that "J". Spelling isn't altogether clear either – Koojo, Kujo, Coojo, Cujo?

The main problem I see, however, is that Cujo is a murderous dog in a Stephen King novel. Since most searches for Cujo will aim at that meaning, your site will be perceived by Google as usually irrelevant in comparison with searchers' intentions. And that doesn't help SEO.

Go with the domain that has the greatest brand marketing potential. Don't worry about SEO when it comes to your domain. You can definitely do well with odd TLDs like the .io or others. I've done it recently with mobile development client that has a .us. Their site did VERY well in organic, and still is doing well after over a year.

From experience, adding buyer keywords or call to action terms like "get" "buy" and others in the domain can entice more click thru. Its a call to action in your domain.

The TLD doesn't matter for SEO. The fact that the name is in the URL amounts to one signal among many.

Reference this article for specifics on gccTLDs such as .io:
http://searchenginewatch.com/sew/news/2266224/google-starts-treating-more-countrycode-toplevel-domains-as-generic-tlds

Whatever your domain dosent matter, its depend on your marketing and search engine optimization and you unique contents- that will give best traffic and higher rates if targeted audience in your website ..as per google parameter .

There is nothing like a particular domain is successful and will have higher SEO chances. SEO depends on the content present in the articles. Article marketing is a way for you to generate interest in your site by someone first reading an article that then guides them to your website. You can think of it as one way of building the reputation as an expert in your field. If you can do that your SEO will have a higher chance as well.
Besides if you do have any questions give me a call: https://clarity.fm/joy-brotonath