I liked the silver one best myself followed by the blue, it's too bad they couldn't keep it longer because of the collar. The blue one looked closest to a Starfleet uniform, and the brown one just looked...brown. I don't know why they couldn't decide between the two for a while. Unless of course it was because they were implying that they were civilian clothes, and Seven had different stylistic preferences on different days.
Still, the ones after the silver were just so ridiculously thin.