Personally I'd like to see the Czar's crash damage buffed to 12k (currently 8k), so that it's more reliable at squishing the enemy because, at the moment, every T3 shield mitigates 3K crash damage thus if the Czar crashes over 1 shield, it can't cascade T3 pgens and T3 mass fabs. The Ahwassa on the other hand is faster so there's less time to shoot it down and can do 20k damage if it crashes onto its bombing target.
If the enemy don't have lots of AA the Ahwassa is still better because its AOE bomb can do far more damage far quicker, especially if the player knows how to hover bomb. The one thing the Czar does better than the Ahwassa is its massive AA range. I'd like to see the doughnut of doom also be better at dying with style.