Yeah, my favorite Q3 engine game was Jedi Outcast (the engine must have been licensed, since the game was released before 2005, when it was open sourced)
johnisgoodOP
My childhood game from ioquake3 was Tremulous and a bit of Urban Terror, around the age of 14.
Side-note: before that it was Armagetron Advanced, but that has nothing to do with Q3.