The best in my opinion is the rent/trade board on these forums. There does need to be some trust on both ends, but you aren't paying a broker, just whatever payment processor you use.
Many options.
If you don't mind doing everything yourself, renting here is an option.
Otherwise, Davids or other online sites that do everything for you.
The intermediaries keep anywhere from $3-$4 per point on reservations that they broker. None of them pay you 100% upfront. They all hold on to 25%-30% of what you're owed until the renter checks in or completes their trip (depending on the broker). At least one will supply you with a 1099 form to file with your income taxes.
Absolutely agree - you get less for the points with little work if using a rental company, you'll likely get more from renting on social media but will put in significantly more work (a LOT of impossible requests for things such as AKV Value Studios a week away, BWV Standard Studio during the F&WF 8 months prior, etc , etc, as well as verrrry low ball offers).
My points have gone pretty quickly on the Dis R/T forum, for more than a broker would give but $1-2 less than on FB. Bonus is that you get to deal with some really nice people here!!
If you do end up using a broker, choose and read the contract carefully. I know at least one broker changed its contract to put the burden of cancellation not initiated by renters entirely on the owners.