The way I see it there are three choices for an Axis heavy bomber. One from each of the three big Axis nations. (One of these may be impossible for HTC to get the information required to add it to AH)
Heinkel He177A-5 Greif
Engines:2 x 2,950 hp (2200 kW) Daimler-Benz DB 610A/B engines, each comprising of two 12-cylinder inverted Vee DB 605 engines close-coupled to one propeller
Crew: 6 men
Performance: Maximum speed 304mph at 19,685ft
Initial climb of 853ft per minute
Service ceiling of 26,245ft
Armament: 2 x MG151/20 20mm Cannons
3 x MG131 13mm machine guns
3 x MG81 7.92mm machine guns
Ordanance:This was a point on which I was led to believe that it could carry 13,000lbs of bombs, but was then told that was not so. I will need the Luftwaffe specialists to fill this data in. What I have is this:
1,000kg internally
2 x Henschel Ms293 missiles
The He177A-5 is the biggest, and save for reliability issues (which would not come into play in AH), the best German bomber. Many fans of Luftwaffe aircraft have requested it.
Pros:Fastest of the three
Largest production of the three
Good defensive firepower
Extensive use in WWII
Cons:Slow climb rate
Potential Issues:Getting the Henschel Ms293 missiles to be workable in AH
Lack of clarity about the payload's size and makeup
Kawanishi H8K2 "Emily"
Engines: 4 x 1,850hp Kasei 22 Air-Cooled Radial 14 Cylinders Engines
Crew: 10 - 13 men
Performance: Maximum speed 290mph at 14,750ft
Climb to 13,125ft in 8 minutes 53 seconds
Service ceiling of 28,750ft
Armament: 5 x Type 99 Model 1 20mm Cannons
7 x Type 97 7.7mm machine guns
Ordanance:Maximum payload of 3,000kg
16 x 60kg bombs
8 x 250kg bombs
2 x 800kg bombs
2 x 1500kg bombs
2 x 800kg torpedos
Until a few days ago I didn't consider the H8K2 to be a real competitor in the heavy bomber role. The information I had seen up until then stated that it carried a maximum of a 2,000kg payload. Mitsu's info has shown that the H8K2 has a 3,000kg payload and is a true competitor in the heavy bomber category.
Pros:Most durable of the three
Good defensive firepower and arcs
Great climb rate for a heavy bomber
It is a flying boat
Extensive use in WWII
Torpedo capable
ConsLow production numbers
It is a flying boat
This thread about the H8K2 is the best thread I have seen in regards to an aircraft in a long time:
H8K2 Emily InformationPiaggio P.108
Engines: 4 x 1,350hp Piaggio P.IIX RC 35
Crew: 6 men
Performance: Maximum speed 261mph at 12,800ft
Climb is unknown
Service ceiling of 26,400ft
Armament: 8 x 12.7mm machine guns
Ordanance: Maximum payload of 3,500kg
Specific payloads are unknown

The P.108 would be a definate departure from the expected, but it would probably be the most difficult to do. Data on this aircraft seems to be very limited.
Pros:Heavy bombload
Good defensive firepower
Would be unique in the simulation world
Cons:Very low production numbers
Very limited use in WWII
Slower than the other choices
Potential Issues:Limited available data on the interior and on performance
What do you guys think?