Evernote positioned itself as a "second brain", but turned out to become an awesome Digital Vault. You can throw anything at it and Evernote will happily ingest it. You have blazingly fast search backed by Evernote cloud services, and even have some note linking capabilities but they are rudimentary when compared to a fully fledged PKM like Obsidian, DEVONthink, or others. These newer PKM tools allow you to reflect and reason on the content you have and massage it in ways that surface new ideas and allow you to follow unexpected relationships (hence being a true second brain). This is much more harder to achieve with Evernote.

Both are valid and powerful tools but the use cases are different, maybe just because the definition of "second brain" has moved since Evernote was conceptualized on the 2000s.

If you like Obsidian, check out Logseq. Both handle plain-text Markdown, so you can use them interchangeably. Logseq also handles Org-mode files, if that’s your thing. Everything is local, but works well with cloud storage. There’s also an iOS app. It’s worth a look. (No affiliation)

https://logseq.com/