The amount of spam and attack we deflect deflect from Hetzner IPs makes it hard to believe what they give out is guaranteed to be a clean IP. Just in the last 48 hours we firewalled over 100 of their IPs because of continued spam. It comes in waves, for sure, but still.
That said - there is no perfect host. NONE.
We're on AWS and have very few issues - none that affect our SM hosting. The only issue with AWS is you have to petition to get your outbound port 25 opened. We got ours because our mail servers had been online for over a decade on other hosts prior to moving to them and don't appear on blocklists - that was our only leverage on that.
MailEnable survivor / convert --