I'm going to recomend you stay with 365! i will ttry to answer your criticisms and then tell you the banger at the end
> The email service should be able to handle automated emails that I'm using to provide my service.
365 has SMTP and can send automated mails, but sending bulk mail from any mailbox service does not scale. I use Mailchimp for mailing lists and Mailgun for sending from apps. Mailchimp and mailgun are scalable and wont get you marked as a spammer.
365 mail has a killer feature, more below.
> Simple task manager
I tend to reccomend Microsoft Planner and Tasks for the kockout reason below.
> File sharing: Once again, I'm using Office 365 but it is shitty service
File sharing with who? Your team? or the world. Remember you have Sharepoint with Office too. What do you find shitty? Everything that is true of Dropbox is true of 365, but 365 has a killer feature below.
> Messaging:
Teams, and here is the killer feature of 365. The filesharing of Sharepoint and Ondrive, the Tasks from Planner and Todo, and your emails are all completely integrated. So you create a project team, it gets an email group, its files on Sharepoint are shared with all the team members. Your Teams meetings appear in your Outlook Calendar. You also get the best Spreadsheet app going.
As your business scales being able to manage all of this through a single directory service will matter more and more to you, and the fact that there are more feature rich versions of all of these apps in the market will matter less and less.