The Lancaster was designed as a day bomber but quickly switched to night bomber, a role in which it was much more effective. A Lancaster would have performed as well as the B17/B24 at day bombing, but was clearly superior at night.
Actually, the switch to night bombing/area bombing was a necessity, not a matter of superior technology. The US forces would have had to switch to night bombing too, if the fighter escorts had not been available later in the war.
Altogther, although the B29 was a better aircraft, it wasn't there when it was needed.
Hmmm, the B-29 did not have any bases to fly from till 1944. And, ironically, most of its work was done as a mid to low level night bomber. They tried daytime high altitude bombing, but the extreme jet stream over Japan made that totally ineffective. Night bombing with incendiary bombs was not "nice", but it was very effective, just ask the citizens of Yokohama (most of the city razed to the ground by bombing/firestorms). B-29's also performed very effective mining missions, sinking over 200,000 tons of shipping in April 1945 alone.
As a personal view, each bomber is made with certain missions in mind, and it is not a slam that a aircraft is does not perform a mission for which it was not intended. The requirements for the B-17, B-29 and Lancaster were each different, and the designers approached them in a different fashion. I also believe the poll should not lump 'tactial' and 'strategic' bombers together, since the missions that they can perform are much different. Can you imagine a Lancaster/B-17 trying to perform as a torpedo bomber?