I think the best would be those with a common theme, but a completely different vibe ex.
Vlastimil/
Patrick,
Florian/
Gulzar,
Gregory/
Ira, etc.
I agree with
Andromache about using variants of the same name. This might also apply to anagrams (though I
LOVE Claus/
Lucas).
Anyways...my favorites would be:
Henry/
HynekClaus/
Lucas (really handsome)
Vlastimil/
Patrick ( I dislike both names but I like how different they seem to be)
Victor and
NikolaVendelin and Slávek