An aikido master the size and strength of seagal would be a formidable opponent indeed, don't underestimate aikido, it is all defense and using the opponent's aggression against them, it is an almost flawless form. Seagal is not such a surprising mention, but in retrospect to what I said above, there is nobody like Bruce Lee, lets not forget, he is the only Kung fu master in centuries to improve on a classic form (what he called keet june do), and give birth to a new form entirely. I think Bruce Lee's power and speed would allow him to beat Seagal in any kind of contest, but make no mistake, Seagal would mop the floor with Jet Li.