I like my Excal a lot, but I don't see why it's ranked up there with Anni/Apoc
Probably got something to do with the Fusion properties of KoH.
It's also a nice option to pack some additional damage on PLD when doing Aminon, without walling the other proper DDs.
Bet those are the reasons why some people value Exca so high.
Too much, in my eyes, but at the same time I acknowledge those niche values.
As for Kikoku it's a pretty nice option for NIN when soloing or lowmanning.
One of the best option I would argue, clearly not on top but given how Relics are usually way further behind in tier list for pure DDs, I can understand why Kikoku might look better than most other DD relics.