From Memory Alpha based on Best of Both worlds, 40 ships were sent, Drumhead established 39 were destroyed, Scorpion references a Captain Amasov describing the Borg after an encounter with his ship. This encounter occured before Voyager, not directly saying but the log entry Jane way read implied what and when it occured. Based on that the Star Trek Encyclopedia suggests the Nebula Class Endeavour NCC-71805 survived the Battle of Wolf 359.
While not canon, the game Star Trek Borg depicted another survivor, the Excelsior class USS Righteous. This interactive game was directed by Jonathan Frakes and stared John de Lancie. It was released in 1996 before First Contact which Frakes also directed. Since the game is not playable on Windows 7 or Vista, I will tell you that the Righteous was originally destroyed in the battle. She was part of the third wave of ships along with the Saratoga, Kyushu, Melbourne, and Tolstoy. However, the player saves the Righteous which is then tranported 10 years into the future by Q in order not to contaminate the timeline. The game is unique in that it shows the assimilation process from a first person point of view. It also shows Q as a Borg! I wish the powers that be would update it to play on current OS and remaster the video/audio. Admiral William Thomas Riker 21:22, July 26, 2011 (UTC)