I would say Tu-2S isn't the Best bomber... it is the most efficient as long as you are willing to return to the base and not having a fast ride home when 10 fighters rip you apart at 10K over an enemy town.
I'll explain.
When you fly a bomber one of the most important factors is how many targets you can destroy/drop bombs at important target for a given amount of time.
To fly B-17/B-24/Lancaster efficiently (with good chance to return home) you need to climb high enough, accelerate in a friendly environment, setup your course to relevant targets, i.e. get information about what is still needed to be destroyed - which hangars/town and hope that the data would be still relevant when you over a filed), pass over your target destroy what needed make sure you look around, escape safely and land to go for the next target.
For correct B-17/B-24/Lancaster bomber flying each turn around would take at least 30-40 min. Because, climb takes time, acceleration etc. In many cases the information wouldn't be up to date because: hangars were rebuild or already destroyed, the base captured so you need to turn to another field hoping that the bombs would actually be useful (i.e. there is an attack on the field)
Now when I look on Tu-2... in comparison to the all the bombers I mentioned above:
1. It climbs much faster
2. It cruises much faster
3. It has similar bomb load
It significantly shortens turn around time. In the time B-17 runs one sorties I'll complete two. Having higher speed is much better defense than having better weapons (Ar-234/Mosquito XVI). If you navigate correctly have enough altitude and speed the chances of being intercepted are much lower. And even if somebody gets to intercept you, most likely he would be in your rear zone.
So it becomes very efficient plane for pilots who wants to live.
BTW my favorite bombers are (not in particular order):
Tu-2S, Ki-67, Boston, Mosquito XVI, Ar-234.
If you take a look on Boston vs Tu-2S performance charts you'll how similar they are in their performance, but Tu-2S has better bomb load and better defense armament.
They are all great in getting to the target without being intercepted, make a damage and escape (and to it without get bored)