I can only contribute my own experience. I have a dedicated server with an IP address in a datacentre, with approx 6 users using my email server for their primary email. DKIM/DMARC/SPF all configured correctly. I also have policies that suspend logins for accounts if they send too much in a certain timeframe, because this is a pretty good indicator of account compromise. The limits would never be hit by humans.
I've had three issues. The first was delivering to outlook.com, but this was temporary and resolved relatively quickly: I simply contacted their support. At the time, they didn't bother to validate DKIM or DMARC according to their headers.
The second was a sender sending to us with a misconfigured SPF policy. I had quite strict rules that spf failure => user's junk folder that I had to relax, but I also had a discussion with the admins at the sending company to explain the issue.
The third was yahoo. For reasons known only to them, they decided that IPs they've never seen before will be blocked by returning an smtp deferral that is permanent, which is bad for legitimate mail servers because the email remains stuck in the mail queue forever. I ended up discussing this with their support also and after some discussion that block too was removed.
That's pretty much it. I receive dmarc reports now from many providers so I've an idea what percentage of our email is quarantined or rejected (none). I've been running email since 2011, for my own main email and a few others. I don't think deliverability is that much of an issue and I was able to resolve all the problems I've had in 10+ years of doing this by emailing support, explaining myself and asking to be unblocked. Usually this simply resulted in "OK but if you do bad things we will block you no guarantee of inbox delivery etc etc etc". That's fine. It seems that there is a large degree of per-account spam filtering as well at the big providers mapping to individual users' preferences.
Of course, if you don't set up SPF/DKIM/DMARC, or you have an IP with poor reputation (you can check the DNSBL) or worse a residential address, you will have trouble. I would generally look for a provider that has a relatively strict acceptable use policy, and in particular doesn't allow VPN endpoints to be run from their infra for your email, to reduce the chances your IP has a terrible reputation with the big providers. Also, join all the sender programmes, set reverse dns, don't let your users do things like send bulk email and that will reduce many of the problems.