What do you consider 90% garbage sites? I guess there is an infinit number of ads/tracker/malicious sites out there. Of course having 4 mio domains on blocklist will potentially cover more than "only" 200.000. But the number of domains in your blocklist is just a surrogate parameter - what really counts is having "all" garbage domains on that list that you will really visit.
I have ~300.000 on my blocklist and in the last 90 days only 1150 different domains have been blocked.
To answer which lists are really good for you, I wrote a script
The one list I benefit the most from is:
https://www.github.developerdan.com/hosts/lists/ads-and-tracking-extended.txt