I keep all my passwords in a text file. I can't imagine remembering them all. I suppose I should keep that file encrypted and synced to multiple devices with rsync or so. Would a password manager give me any advantage over this scheme?
It will allow you to organize the passwords in a hierarchical way with folders (banks, administration, forums, whatever), and set icons.
It will also keep the date of the last time you modified it. Sometimes this can be useful to know if you are impacted by a breach revealed after the fact. You can also make passwords expire if you like.
You can also add extra data in a way that doesn't clutter the main view. This can be interesting when credentials are more than login/password. For example you could add a PIN there. For my car radio there is a code to enter to make it work after the battery dies, I added the entire procedure to the extra data as I always forget it and it's not intuitive.
I just checked, I have 957 passwords in my KeePass.
1Password can also store other information besides passwords such as credit cards, software license numbers, passport numbers, etc. There is also a secure notes feature for storing arbitrary text.
The other password manager that I tried before 1Password is Lastpass. I ended up choosing 1Password since I think it's better designed and overall feels slicker. The /r/lastpass subreddit is littered with complaints about broken updates and bugs...
https://www.passwordstore.org/
It uses a similar philosophy of encrypting plain text files and you can sync them how you wish. It might do some of the 'heavy lifting' for you.