If you create 2 accounts, each account would have access to their own speaker(s) and not the other(s). If you create one Sonos account, any user can choose to play on the speaker that they want, without any rigmarole of reconnecting to a different account. All speakers would be connected to that one account.
Using a single Sonos account, then following the instructions in the linked account to set up individual ‘users’ would be the way to go. Each user would default to their own ‘music’ and not see the others, without a pull down choice.