If we allowed to include spouses and former spouses, than the Windsor I have to say I found the most trying and irritating was Diana, Princess of Wales!
Amongst those born in the purple, I find Andrew rather too self centered and the Earl of Wessex has this dreadful ability to appear as though he is suffering from an appalling dose of 'self entitlement! I think they probably got that from their dreadful maternal grandmother, whom I could never abide and always thought honed her 'motherly' image to the nth degree in order to obscure just how hypocritical, self centered and unpleasant she could be and was!
I think Princess Margaret was actually probably more like her mother than many people care to contemplate, the only real difference being that Margaret never cared to try and be popular nor did she have the savvy to adopt an image that would make her appear 'motherly' and chocolate boxy like her mother or as Diana did! Other than that I think they, QEQM and Margaret particularly, were probably very alike indeed!