Definitely Obito's Sharingan... Kamui is the most hax MS ability, and literally the best and coolest one. Kotoamatsukami and Tsukuyomi are also good but Kamui FTW.
if I had to choose seriously I would choose Obito's just for a design... those sharp edges looks so badass just as you can see on my av but the lack of Susanoo always gets me... MS without Susanoo is just meh...
Obito's techniques are the best in most situations. I don't know why Madara is listed though. We don't know what his are besides Susano'o, and this isn't about designs.
Kamui is the greatest technique ever to leave kishimoto's pen. 1 ms jutsu can troll the multiple gods of nv multiple times. can't say that about ama,tsukuyomi,ka,or any other tech period.