They not only have poor spread, but low damage output and poor reload rate. The only thing they have is a slight range advantage over the 14.96" trips, which is just not worth the drawbacks. This is why you see so few players using the guns - they're just not balanced like the IJN 20" for the Shinano, failing to do anything to make up for the low barrel count. With 6 guns, they need to be far superior to their current state to be worthwhile.
Back to OP, I hold the O-Project II (1942) to be the better choice for leveling due to the extra support slot. And, with a lighter crew, it can easily get to 44 knots. The ship also has more options with setup and play style, whereas the Bismarck 1943 is a one-trick pony.