I prefer FICS too, compared to web alternatives like lichess, you also get a glicko rating, history, win-loss count, lag stats, and you can find a game in an instant, as well as chat functionality and more.

The FICS database of games is also available on: http://www.ficsgames.com/ - currently hosts about 120 million games in its archive.

Best client for FICS is Babaschess - http://www.babaschess.net/default.asp