It all depends on what the purpose is.
Well quite, note the caveats in my original post please.
If you're printing large then obvs medium format is the way to go. Saw some of Vivian Maier's Rolleiflex negs printed large at Photo London this year and they were stunning.
However, printing A4 or smaller (or just posting on the internets) from a fine grained 35mm neg shot on sharp glass the difference ain't going to be that great.