Why don't you make it so the thread can only be bumped once per day regardless of how many people post in it? I think if we make it merit or rank-based then they'll just find a way around it by paying the relevant users to post in there. That would at least the defeat the purpose of paid bumping and it'll probably stop whilst still allowing active threads to be bumped daily (but just once a day. The time could also even be randomised so people can't just choose a certain time of day to bump it).
So it would be essentially a random list of threads that were posted in at least once in the last 24h. I kinda like the idea of it being less random and more merit-based.
For example, If I report 10 posts in one thread and they are marked as good, then the thread should taken down from the first page.
That can be abused to kill a competitor's thread.
And this too:
Maybe the average of the users (from past24h) total earned merit.?
If thousands of newbies start spamming" good project", the average user merit will go down, reducing the score.
A couple of months ago I suggested something similar, but for the Bounty section (see
Where to run a spam free bounty campaign? [new board?]). The idea was to use the earned merit in a 48 hour period to establish the sort order, but I did complicate the idea by allowing the screen to have a section ordered by the merit criteria, and a section of the screen ordered by the conventional last post criteria (in order to allow both criterias to coexist and not give full power to merits).
This sounds interesting and is probably less prone to abuse. Someone would have to
spend merits to keep the thread on top and not just buy/farm a few accounts.