Flat CB's are awesome. We won 4 tournements in a row this fall using nothing but the D12's and D20's. We live in Michigan and fished fall divisions throughout Sept and Oct this year. The D12's work really depth accurate on 10lb line until the water temp drops into the low 50's and below. Then I start with the D20's to cover the same range. As for color that depends on your preference but I prefer the white it has always been my go to color.
Let me know and I can help more if needed.