Maybe their spam filtering is worse, but they also block way more legitimate smaller mail servers for no good reasons. Every few months I have to send an appeal to them so that I can continue sending mails from my mail server. They claim that there were user complaints about spam but it's pretty much impossible. I think they just silently blacklist smaller mail servers periodically and hope that they can fight spam that way. Obviously they can't.

So if you want to be able to receive emails from smaller mail servers - don't switch to Microsoft.