The company states that only a limited number of employees will be able to look through your notes, all of them having passed background checks and having been trained in security and privacy, but we have no guarantee about that. Furthermore, when asked if the users' data will be anonymized or not, Evernote declined to answer, so this probably means that those who read your notes will also be able to tell exactly who wrote them. What's even worse is that individual users won't be able to opt out of this process; even if you opt out of the machine learning features, your notes may still get read. The only ones who can stop the company from reading their notes are Business clients, but if they choose do so they won't get any potential new features.
If you're looking to keep your privacy, but you don't know what else to use, a similar service called Bear recently tweeted: "Fortunately bears *can't* read: they are the best keepers!", so it sounds like a good place to start. Additionally, Microsoft's OneNote may also be a solution worth looking into.