Please post the times from sea level to 15k of all three when loaded with their typical bomb load and fuel load.
"Typical fuel load" is quite a vague term. Different players might have different ideas about that. What is a "typical" Lanc loadout ? 25%? 50% Is 75% a 'typical' fuel loadout for the B-29 (for me, it is).
When comparing capabilities, you ideally look to have some standard, in this case to select a fuel loadout that gives roughly equal endurance.
A He-111 with 8x250kg (4,400lbs) and 50% fuel (=1.1h) will climb to 15k in about 21 minutes from SL.
The B-26 (4,000lbs) and 100% fuel (=0.9h) - 15 minutes
Lancaster (14,000lbs), 50% fuel =(1.4h) - ~21 minutes
B-17 (6,000lbs), 50% fuel (=1.2h) - about 17 minutes
B-24 (8,000lbs), 50% fuel (=1h) - ~17 minutes
B-29 (14,000lbs), 50% fuel (=1.4h) - ~18 minutes. Even the heavy 8x2k loadout at 75% fuel (about 2h flight time) takes as much time to reach 15k as the much shorter ranged He-111
I think I can pass on posting Ki-67, G4M or Mossie data
The He 111 is not a good climber for bombers at all, unless you are distorting the comparison by giving it a very light fuel loadout only suitable for very short ranged runs while loading up the other bombers with fuel for a long range mission.
EDIT: Quick time vs altitude chart. 30 minuets of climbing time from seal level
