I live in London and have used over 100 times, each of Heathrow, Gatwick, Stansted and Luton. Luton always feels cheap, overcrowded and unpleasant. Stansted feels just about bearable. However Gatwick to me feel good enough - certainly good enough not to need to spend more of my own cash on a higher fare from Heathrow.
I realise that Gatwick doesn't really do connecting flights to a time-poor passenger, but what is it about Heathrow that attracts the O&D people in the pointy end compared to Gatwick ? I know this happens but am puzzled as to why. Does Gatwick just need better lounges ? More high end shops full of bling ? Is it a branding thing ? Snob value ? Answers on a postcard...