I like both names, but to be honest I much prefer Jonah. I just prefer the sound and look of it and also think it fits in better with Oliver, Clara and Tobias. I don't think Clara and Jonah are too similar at all. I like the following combos:
Jonah Raphael, Jonah Eric, Jonah Lawrence, Jonah Gideon, Jonah Luke, Jonah Seth, Jonah Samuel, Jonah Sebastian, Jonah Finley, Jonah Frederick, Jonah Michael, Jonah Matthew, Jonah Maxwell/Max/Maximilian, Jonah Benjamin, Jonah Zeke, Jonah Brendan