I guess it depends on your idea of "pretty"! I really like the Stampers Anonymous Grunge Flakes
set - four different flake designs and two sizes of each flake makes it very versatile and the flakes are beautifully detailed and naturalistic. The smaller flakes come as one strip like a border but I snipped mine apart to make individual stamps. I later read Tim Holtz say that they were intended to be separate but the set was cheaper if they manufactured it with them as one strip.
Have fun finding your perfect snowflakes!