Some of these are terrible from a design point of view. 3 are just a coat of arms slapped on the National flag, Brandenburg is just the flag of Hesse with a coat of arms on. Berlin is almost fine, the bear in the middle is stylised enough to be recognisable on a flying flag. Thuringia and Hesse are the same thing but the other way up, same with Saxony-Anhalt and Baden-Wurtenburg. Hamburg is iffy, I don't like the design in the middle, just too complex to make head or tail of if it's flying in the wind half a mile away, much like Berlin and the other CoAs.
The rest are decent with obviously Bavaria taking the top spot for being instantly recognisable and so simple a child could draw it. Bremen takes second place. The other 4 equally placed ahead of the rest, though I like the colours of Saxony.