Had a gold 2015, rose gold 2016, and now a silver 2017 (following my policy of "get the new colour, or if there isn't a new colour, get silver" 😛 )
They're all nice, though personally I'm not a fan of space grey at all.
However, in my experience if you get anything other than space grey, you take a hit on the resale value. Most people seem to want that colour.
So, silver will probably hold its value better, but still not as good as space grey. In which case, choosing between silver and rose gold, it's probably best to just pick the colour you were first drawn to, and not worry about the resale value! 🙂