Blackbeard's isn't legit in power, he needs to negate other DF's. The way he does it really doesn't make sense either. I don't underestimate kizaru one bit, but he can be countered. If he ran into Kuzan, he would freeze. If he ran into magma, he would melt.
I disagree. The Yami-Yami no mi is a full blooded Logia DF meaning that he is capable of having attacks phase through. In addition, he has shown to use attacks outside of negating other people's power as shown when he was sucking people in at Marineford if I recall correctly.
What makes Blackbeards a top tier....is the FACT that he can negate powers....that's completely unfair in combat because he maintains his power.
And for Kizaru...he won't simply "run" into them. He also has Haki so he's going to be able to dodge them if he so chooses. Lastly, if Haki embued attacks do work...then Yasakani no Magatama is a rediculously OP attack to use on his fellow Admrials/Logia users...its just a barrage of light attacks. He doesn't entirely have to get close.
Whitebeard was able to grapple Akainu without suffering immediate consequences, so I'd imagine a simple light speed Haki kick isn't doomed either.
Light speed is insanely OP...which is why probably the laziest person has its ability...to keep it from being OP.
EDIT: I'd say on a side note...I doubt Kizaru went all out...he still had his "Screw This" attitude. Kizaru doesn't need an Island destroying scale ability BECAUSE his attacks can be so pin-point accurate and fast that you really can't stop it.