You can honestly start wherever without missing out on too much, but DS1 is still a great starting point since it lays the foundation for some lore stuff that's explored more later in the series. That's only if you're okay with it being a lot more clunky and slower paced due to it's age though.
If you're willing to risk the money or have a safe way to get it for free, Elden Ring might actually be the best one to start with. It has a few good QOL updates and if you get hard-stuck on a boss you can almost always go explore somewhere else much more easily than in DS. Also the story and lore are brand new so it doesn't matter if you've played the other fromsoft games.
You can honestly start wherever without missing out on too much, but DS1 is still a great starting point since it lays the foundation for some lore stuff that's explored more later in the series. That's only if you're okay with it being a lot more clunky and slower paced due to it's age though.
If you're willing to risk the money or have a safe way to get it for free, Elden Ring might actually be the best one to start with. It has a few good QOL updates and if you get hard-stuck on a boss you can almost always go explore somewhere else much more easily than in DS. Also the story and lore are brand new so it doesn't matter if you've played the other fromsoft games.