I prefer Heathrow for convenience, but the Gatwick experience is superior if you have Silver. The premium security is always fast and the lounge has never been crowded whenever I've been in, which isn't something that can always be said about Heathrow. The cost of parking is also merely unreasonable rather than eye-watering. Without status, Heathrow edges it - I find the South terminal quite run down and it always just seems a more stressful experience than Heathrow. The restaurant options are however better at Gatwick.

I am not sure I'll manage to hold Silver next year, so my preferences will likely be adjusted.