Dynamics 356 licensing/subscription guidance

Hi all,

Could you recommend us what is the best Dynamics 365 subscription to buy that meets our needs? 

We will be using only Sales module + Activities +  Dashboards + Reports

1. There will be 5 to 7 users, in office using CRM every day - Using outlook.
2. About 20 users who will connecting on their phone - to do very basic operations like creating records with some attachments, editing record.