A new TF2 lobby website called TF2 Stadium has open for Beta testing. It looks to be well constructed with some nice features. Players ready up ion website before joining the game, a key feature for lobby sites. Sign in by steam, and give it a good look.
From the TF2 Stadium website:
Lobbies are semi-organised games between two teams of players in a mock-competitive environment. They're a great way to get a feel for the competitive format of TF2 without having to join a league or organise a team. The two major formats used in lobbies (and competitive as a whole) are 6s (6v6) and Highlander (9v9)."
https://www.tf2stadium.com
coming soon...