I vote Soi Fon. Someone would be hard pressed to beat her in melee combat.

I hope Shunsui wins though XDD

Soi Fon most likely has the best swordsmanship of the three because Melee and Fighting are different still I imagine this might be difficult but my guess is on Soi Fon winning.

Soi Fon's a great melee fighter, don't get me wrong, but Ulquiorra, I would say, far faster and stronger. Whether he's more skilled or not is certainly up for debate, but if we're talking about a head-to-head battle with nothing but melee skills in use, I think it's doubtless who wins it.

I like Ulquiorra but Shunsui took on/defeated Starrk Coyote a.k.a Espada #1 when Ulquiorra is only #4 and Soi Fon might be a good swordsman but
1. She only uses 1 sword
2.Shusui can attack from the shadows
3. I'm sure his Bankai isn't a one time use type

True enough, though everyone underestimated Ulquiorra's strength since no one knew about his Segunda Etapa. One could argue that he belonged at the #1 spot.

Not just because he's one of my all-time favorite characters, but also because of his boundless and inmense power, countless skills and abilities (not only swords and direct contact), clear and unique fighting style and his BEYOND OF IMAGINATION techniques. ^_^

Shunsui, I think, would be slightly better at melee combat than Ulquiorra... Soi Fon, I'm afraid, is better suited for sneaky melee fighting and not so much to counter against someone with the experience like Shunsui, or the raw power, like Ulquiorra. However, if it came down to who would win in a fight between these three, it would doubtless be Ulquiorra.