The worst are the ones Borrelli uses, which are too damned thick for their tiny buttonholes and which have very sharp edges that dig into your fingers when you try to press them through.
I avoid my Borrelli shirts cos i hate buttoning it up...its painfully difficult.
Kiton has nice large buttons and commensurately large button holes.... and very very easy to button close.
PS. Cant believe I just put this much effort into buttons....