I think it is better to play in a site with less player for the free rolls, because the chance to win is higher, and also the freerolls will end faster, saving some time rather than wasting alot of time to play and move on to the next hourly freerolls
Most of the famous sites like Seals and Nitrogen usually has a lot of players in the freerolls, however the hourly freerolls aren't always so occupied. You can check out freerolls on new sites like AllinCrypto for freerolls with less players.
They also have a 2 BTC freeroll coming up soon, but I think you needed to win tickets for that with ticket freerolls happening on the site.