Re: Joke right?
"Most decent web-based services online have an option to sign in with a Google account. "
That's not single sign on. That's multiple use of the same sign-on. Single signon is transparent and automatic. And pretty much any SaaS you might want to sign onto say - for example Sales-Force - will support Microsoft SSO.
"There are many project management tools that are leagues ahead of the shoddy sharepoint experience."
Because SharePoint isn't a Project Management tool. Microsoft Project Server is though and it's also a long way ahead of most of the competition. As an Enterprise programme manager I have never heard of Basecamp and ApolloHQ - so I'm guessing they are not enterprise grade solutions like MS Project, Innotas, HPE PPM, Clarizen or Clarity that I am familiar with.
"True, from a purely box-checking point of view they do have more integrations, but the integrations are usually significantly worse than how other companies will integrate"
Nope - with Office you have local plugins with API level integration that's simply not possible with Google. Try running say Condeco (market leading meeting room / front of house booking system) with Google Apps, lol. Or Sales Force. Or numerous other market leading enterprise tools.
They limitations with Google's products are everywhere - for instance max 25 people in a hangouts meeting? Surface Hub pisses all over Chrome Box. etc. etc.
"Microsoft Teams is a good example of this- from a feature point of view it looks like it can compete with Slack"
So much so that Slack have had to take to copying features from Teams like threads. Later this year, Microsoft going to add all the functionality of Skype for Business into Teams and there will be no comparison.
"Microsoft Teams is really quite shocking. I tried it at our last company and it's just not reliable at doing the one thing it should: ensuring the user you are chatting to sees the message"
Only if they turn off or ignore alerts. Otherwise it works perfectly - we already moved to from Slack to Teams at the beginning of this year as it's effectively free with O365.
"The only decent things are: Word, Email, and Calendar functionality."
Excel is miles better than Sheets, Skype is way better than Meet, Google presentation software is a joke, and I don't think they even have a SharePoint product. Not to mention that O365 performance is much better as it's local, and if you loose your internet connection O365 still works as it's a local install, whereas with Google Suite you are stuffed. Google is also utterly lacking in the DRM and encryption management space compared to the many options of Office. The best you can do with Google is send an ACLd URL! And their compliance capabilities are laughable.