I cannot state strongly enough, that blocking entire top-level domains these days should come before RBL. *.top, *.link, *.download, etc.
RBL depends on paid or free. Paid: Spamhaus, the 800 lb gorilla of RBL. Also URIBL various feeds. Direct query to a dedicated address with fresh data FTW. Free: I find SORBS pretty quick to list. However I dislike them for their annoying delisting procedures when my SMTP pool gets on their list due to a compromised account. Takes days to get off. Honorable Mention: SpamEatingMonkeys
