Ranking forums:
1) nuf
2) shf
3) rrlf
4) some other forums like, I dunno, wattpad or smth.
5-100000000) other forums of lesser known sites with like 100 active users
...) dead forums
...) satanistic fetishism forums
The very bottom) wn
Nuf about as good as shf. It does have more activity and fewer trolls. It also has some very good long-living threads with lots of discussions, as well as a more active chapter discussion section.
RRL has a forum but I haven't touched it much and it doesn't seem that active.
Wn is garbage, along with all the shit they are associated with, and you should avoid it with a ten-foot pole.
As for the platforms themselves, as a reader, I prefer rrl, since it has more solid ranking systems, it actively showcases reviews and it's easier to find good novels there. SH is good, but trending novels are more about "they are active and alive and probably have smut/bl/gl/gb in them. Check it out", rather than "good shit. Novel updates... It's complicated, I guess? There are more good novels, just because if someone has translated it, it probably means it is worth translating to the translator at least. The novel discussion, the lcd sections also make searching easier and "looking for" probably leads to pretty good results when you are new. After a while, it's kinda... Not bad but less than stellar. Wn is, again, garbage, even to a reader, so I will avoid mentioning it henceforth in this post.
As a writer, I guess both rrl and SH are good? SH has a better UI for reader interaction and actually notifies you when you have new comments/replies, which is great and seems basic enough that it's weird that rrrl doesn't have it. Haven't posted on other sites.
Edit: I know nothing about rrl readers being harsher. The most criticism I have got was an actual review and some typo-spotting (which is a feature there but isn't necessary for SH since here you can just quote). And I write some weird shit at times