Chiara is my number one, both in terms of the look and the pronunciation.
I pronounce
Chiara in the original Italian way,
so it's KEE-ara for me, same for
Kiara.
Kyara with y-spelling becomes KYAH-ara.
I don't care for the others,
Clara as best,
Clare as least one.
Clare without i-inside looks incomplete, IMO; besides the slightly old lady flair.