I'm going to join in with the hive mind here and agree on the last fight being the best. There was the most variety in how you fought him, and, unlike the first battle, it really felt like you two were equals. As weird as it sounds, it was more satisfying to actually be able to knock him down and know that you were doing some damage, rather than your sword acting as merely glancing blows and Ghirahim laughing at you half the time.
Not to mention, the first time I fought him I had no idea what I was doing. There was a great deal of frustration there. I only really beat him because I reverted to Twilight Princess tactics, that is, wildly flailing the WiiMote.