Turbo-electric engine vs high by-pass-ratio Turbo fan, which config. would seem more efficient? (Liquid Hydrogen Fuel)
Turbo-electric configurations do not offer any meaningful advantages for commercial airliners.

Aircraft engines have extremely high power-to-weight ratios. These would be greatly degraded by adding motors and generators.
For instance, the RR T406 offers power in excess of 10 kW/kg. Large turbofans are even better. Most electric generators and motors are worse. The best have the same power-to-weight, but since they only transfer power, this increases the weight of the engine system by a factor of 2.5-3.

Wings are already the optimal location for both the generator and the propulsor.
You want your heavy engine where the lift is created, and that's the wings. You want your propulsors away from the fuselage, and that's either the wings or the tail.
Thus, there is no need to move the power any distance.


Hydrogen is a suitable fuel for turbofan engines and requires no other intermediate devices to convert it to thrust.
There is no significant need for hybrid airliners, as there's no stops to recover energy in flight.
Weight means fuel burn. Engines are heavy: in an A320neo, for example, they take up 14% of the weight. Increasing it 2.5x will make the aircraft 20% heavier. After adding payload and unusable fuel, this results in 15% more fuel burn, if the motors and generators were perfectly efficient.
Since they are not perfectly efficient, a naive replacement would result in even worse fuel consumption. This could be offset by perfecting propulsor size, speed, and placement, but the end result is still that a turbo-electric aircraft will be less efficient than a similar turbofan aircraft.
As to hydrogen itself, it is not the best aviation fuel. However, it is usable. The overall energy efficiency will be worse, due to the loss of cabin space to tanks. Whether that can be offset by clean production is a question outside of aviation.
Regardless, a 15-year horizon is so short that it can be safely said that hydrogen or electric or hybrid airliners will not be anything more than concepts and experiments in this timespan. 75 years, that could be a topic for debate, on appropriate sites.