As for Ju88/He111 comparison: The He111 was harder to manufacture, was slower, had shorter range, and was more vulnerable (debatable). The Ju88 could carry about the same internal load, twice the external load, could carry both internal and external at the same time (doubling the combat load of the He111) and do it at a faster speed, a faster cruising speed, and with a cheaper design. It was simply... "better".
Have to disagree, especially about bombload. Most books list the Ju 88 as with 3000kg, but was rather an exception than the rule. The problem with the 88 was that it's bomb bay was even smaller, and very limited with the size of bombs : the maximum it could carry internally was 1400 kg, and only up to 28 x 50 or 20x 70kg bomblets. In addition on
external carriers it could carry four 250 kg bomb, for a max of 2400kg. The max range in this config was 1260 km; the He 111 H-16 had ca 1900km with 2500kg full load, though the H-16 had about 25% more internal fuel, so they were probably comparable.
That's for the early model A-1 of 1939/40, the A-4 boosted that to 3000kg, but because of the limitation of the bomb bay, this had to be carried externally on 2 x ETC 500, 1000 or 2000 racks, or in some mixed manner.(Similiarly, the He 111H-11 boosted bombload bombload to 3000kg, again in a mixed manner.) Since any decent bomb had to be carried externally, so much for the extra speed (I guess with external loadout it wasn't any faster than the He 111) unless we speak of a light load of small bombs for close support role.
In brief there's simply no way the a Ju 88 from the comparable timeframe would carry more bombs than a He 111; it can be assumed that most of the time they carried about as much on normal missions, the speed difference wasn't great, if any taking into account the Ju 88's external loads, and both were pretty well armored. The plus for the Ju 88 was it's excellent, almost fighter-like manouveribility, and the possibility to dive bomb. The He 111 otoh was more heavily armed, and was easy to fly on one engine, generally carrying more of more potent bombs (8x 250 kg vs. 4x250kgs). In a sense, the Ju 88 was more of a multirole tactical bomber, whereas the He 111 was a very nice, traditional medium level bomber.
