I like the first and third designs. The engine of the first one looks awesome, and the overall shape seems to be simply an evolution of existing planes, but I like how the front and rear wings are connected together to form a single wing shape. I wonder if that would provide increased lift for taking off, since there is overall a greater surface area that lift could act upon?

The second design is weird - would you want to fly on it? I'm not sure I would, it doens't look very stable or strong.

And the third design seems to be inspired by the Shuttle from Avatar lol. Not that that's a bad thing.

What do you guys think?

Well, the last design looks very much like a stealth bomber, so I don't quite understand how this design helps a commercial plane.

The first, design seems to be an improvement of the current designs and my guess is that it is safer in case there is a problem with the engine, as if it blows up, the parts are most likely to spread on the sides (due to the conservation of the angular momentum), thus making it safer for the passengers.

Now the second design, I wouldn't say it is not strong or stable, as it was designed by Northrop Grumman after all, not Joe the Plumber! My guess is that would mainly carry cargo.

Personally, I prefer the first (Lockheed Martin) design and I find the second and third not very appealing .

How much computing power did NASA have when they put a man on the moon? I've heard that there is more computing power in the average $600 laptop than all of NASA had when they put a man on the moon.
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Welcome voopaley
I understand the on-board computer was less powerful than most pocket calculators now.

Meh instead of using jet engines just build a plane big enough for a mini nuclear reactor and use fusion power.

And get some nacelles put on.