I like Shen, I mean, I love when I just walk with 5 enemies on my back and they cant kill me thru half of the map and I just walk.
When you see Shen with full hp "Ahhh shitt we must again waste 3 ults" =)))
But I heard Alistar with ult is super tank, also Rammus, Vollibear?
But then, someone said, that Tahm Kench is the tankiest mothefukr on the Rift. I never played him, but I like to bring troubles into the field, is Tahm the best choice then?