hmm, i always thought it was the hardedge, concidering the poster in my room he's sitting on the bike holding it lol.
actually, when i first played i thought to myself, "hey, why doesn't the buster sword have any materia holes while he's on the bike?" so maybe i just think that because of my poster really.
Anways, i got the hardedge and the buster sword on the bike ingame, ill make some screenies in a bit and let you guys decide what you think looks better.
EDIT:Found a pic of my poster, this is what im talking about. Its kinda lowres from where i found it though.