Modern vs Classic design home construction

Looking to put a 2nd storey on a bungalow and wondering what is the best approach in terms of design. My immediate instinct is that modern design aesthetic (glass, metal, exposed wood) would be more suitable when renovating an existing structure as the designer can leverage existing elements easier than a classic design where it might look more Frankenstein matching up the first and 2nd floors. I could be completely wrong. Any thoughts?