So to start with, I am not affiliated with either site and this is not an attempt to flame WoL.
Facts are facts though.
1.) World of Logs hasn't been updated in months. The only update that we received was to actually be able to upload logs (when fight detection log events were introduced).
2.) Warcraftlogs is already functional and has a fantastic interface with tons of new functionality. Plus, they detect heroic fights all the way!
3.) World of logs is incredibly buggy, with fight lengths, ranks, etc all having issues.
4.) Warcraft logs has a few bugs too, but the developer is actively fixing them. There are updates every few days!
5.) A *lot* of top heroic guilds are now uploading their logs to Warcraft logs, so the ranking data there is probably of a pretty high standard.
I don't understand though why people still upload their logs to world of logs? For some reason people still upload logs only to WoL and not to Warcraft logs.