Well, I know it's called Great Escape and it's the ending song of the 2nd cour of Shingeki no Kyojin. However, the one played at the end of episode 25 was an edited version.
Where can I find this edited version of the song?
Found it! It's track #10 on cinema staff's latest album, Drums,Bass,2(to)Guitars (released 2 Apr 2014). I haven't listened to it myself (the sample is too short to be able to tell the difference between the regular version and the ep25 version), but according to the product description, this is what you're looking for:
This album includes the special version of "great escape" that was used only in the last episode of the TV anime "Shingeki no Kyojin".