I wouldn't think it matters much, Stainless is lower maintenance than copper as its going to stay shiny and all whereas the copper will dull.
I was quite surprised how quickly I was able to chill 10 gallons last night with a little 3/8" by 25' copper. 20 minutes from a boil to 75
Both will work, depends on your budgetary constraints and aesthetic preferences
Primary #1+Auxiliary: Burning River Pale Ale clone
Primary #2: empty
Primary #3: EdWorts Apfelwein #4
Conditioning/Drinking:Brewers Best Belgian Tripel, Apfelwein #3, EdWorts Apfelwein #2, Cranapple Wine, Routers Share Network Closet Strong Scotch Ale, McCormack's Old Malt Oatmeal Stout