absolutely Obito fail.....
Obito could have killed Kakashi in many ways, still he was easily stabbed with a simple and overused Raikiri...
1) Izanagi would not work, because he would be trapt in his dimension
2) Mokuten, some say he had no chakra left, yeah maybe not so much but half of his body is made of Senju DNA, he absolutely should have had enough Chakra for a well placed Mokuten, he also could have used the Preta path to absorb Kakashis Raikiri Chakra and restore some of his own
3)Rinnegan abilitys, the Rinnegan has 6 + 1 paths, still Obito seems not to use the most usefull paths in the fight, also he doesnt need to use so much chakra for the paths because he is an Uchiha, somehow it seems he cant use some of the paths with one eye or there is some other reason why he cant / doesnt use them...
Deva path -> Bansho Tenin, Shinra Tensei on Kakashi
Asura path -> more hands, deadly Lasercannon on Kakashi
Human path -> remove Kakashis soul
Preta path -> restore his chakra reserves
Naraka path -> maybe this one would not be so usefull, still it could maybe stop Kakashi