Agree with clicktechs;
Pretty much every domainer uses Sedo first, then dribble their listings outward to other less-used platforms after that. Afternic used to seem like close competition for Sedo, until around 6 years ago when it seemed that they dried up, at least for sales of 'lower-quality' domains, and now they seem to mostly only be worthwhile for sales of premium domains (premium domains that would sell regardless of where they're listed). IMO.
- This is assuming you aren't talking about PREMIUM domains worth 4, 5, 6 figures. With those, there are a few good platforms that specialize in listing only premium names for sale, these platforms are mostly extensions of blogs by top world-class domainers.
The proactive domainers these days don't rely on just listing a domain somewhere and hoping for offers, they compile an email list for each new domain they get and they forge ahead into the world of cold-emailing likely end users for that domain.