I know its subjective but for me, I don't like the gold at all. I usually like apple's gold but this one is very 1990's gas station fake watch gold to me.
The Blue is new and just like the green, its nice that apple does something different. I don't like it in any cases, even clear ones and it doesn't scream pro to me.
The white is very very white and silver. I like it, although my experience with polished stainless from apple, is that it doesn't age well. I think its a nice phone though.
I like the graphite the most. it looks a tad lighter than usual graphite or whatever dark grey apple makes. It does feel like its the most pro (fessional) of the pros.