Oh gosh that's a good one. In minuscule (lower case) blackletter I like the letters with ascenders and descenders that I can make fancy, y and f particularly. In insular script I like the letter E, it just always flows nicely, and d, because it's so round. I think my least favourite is majuscule (uppercase) A in blackletter script, I struggle to get the angles of the lines right and it just looks kinda boring compared to the other letters.