I'm surprised to see The Last Blade on the list, especially over Art of Fighting, which was a rather formative set of titles for the company -- good call!

(Because it's my pick and I was gonna write it in anyway if the option wasn't there.)

Behind that,

#2) Samurai Shodown (For SS4:S and SS6 in particular, though 2 and 5:S are also great)
#3) Fatal Fury (For Real Bout 2 and Mark of the Wolves)
#4) King of Fighters (For 2K2:UM especially, and 99 and 2k as well)
#5) SNK Vs. Capcom (For Card Fighter's Clash -- my favorite card based videogame.)
#6) Metal Slug (I love the whole series, but I can't sit through any of them anymore. ; -; )

I don't enjoy Ikari Warriors, so I won't bother placing it.