So, I just looked through all of the designs and want to give my 2 cents on all of them.
First of all:
They look awesome, but I'm not sure if they could be used on the Lap, which would be quite the killer for me personally, since I travel around quite a bunch and being able to type there at least for a bit would be nice. (I don't own a 2-in-1 so I don't know if other 2-in-1 might have solved this better)
Now, a second general point:
The Geode & Connect seem "thick" enough that 1 or 2 ports could fit in there. Having 1 more USB-A ports via the keyboard would be nice to see for me (but isn't required)
Finally, to the designs!
What I like about the concept art here is the dedicated button to activate the kickstand. The rubber on the edges is a nice touch, but I don't think it would really help to protect the device.
The power button finger-reader is a dream when using the device in Tablet mode I can imagine, but for the volume bottons I'd like to have dedicated hardware buttons on the side, as I could imagine they're a bit harder to find when you use it with the keyboard.
Keyboard itself looks to be a bit too thin for my liking, I tried the TypeCover of the Surface2 which had too less travel for me.
The backlight are a nice touch and the glass-trackpad too.
If the keys are fabric-like I'd not like it, but if the surface of the keyboard itself are like it, then it's a plus on my side.
The slightly assymetric design looks nice, and the different color for the kickstand is also a nice accent. I love the look of the aluminum body which gives it a very premium look compared to the shield. I'm not sure about the chamfered edge on the bottom if you were to use it without the keyboard, but that's a different theme.
I don't personally like backlit logos, but that is just a personal thing for me.
The volume & power looks more useable than the shield due to being located at the side.
The keyboard-concept looks... a bit weird in concept-41, so I'll ignore that and just judge according to the other pictures.
The trackpad with another color seems cool and easy to see, as well as the color of the keys. While the blue backlight is not my thing and I'd rather have a white one it looks pretty sleek.
I like the idea of the stand for the keyboard, but I faill to see the connection between the keyboard and the tablet.
One super cool feature are the dedicated volume and power-buttons - something that the other concepts lack. The keyboard looks like it has the most travel of all of them, or at least offering a decent thing under it.
There aren't really enough pictures to further give my opinon on to be honest.
My favourite things
I like the keyboard designs of the Geode and Connect.
In terms of Buttons I'd take the Connect.
The port-placement of the Geode is what I like most.
So, my favourites the Geode with the Connect dropping out due to me not being able to see enough of the concept (in comparison to the other 2 concepts) and the longer depth needed without a good connection to the keyboard.
I "dislike" the Shield (I don't really dislike it, I just like the Geode and Connect more) the most, due to: Keyboard-concerns, volume-button placement.
Room for Ideas
When looking at the Kick Stand directly compared to the Connect, I came up with an idea, that might be crazy but could work out. I take that the accessory cases are connected to the Keyboard on the Connect-Keyboard.
Now, if the Table itself had the kickstand, we could fold out the accessory case (which is segmented aluminium or similar) and in the Kickstand were a magnet (or however it would hold there), we could fold out the case, put the kickstand out and then fold the case up like in the Connect-Concept. That would make the device take up more space in the depth, but then again it would be decently to hold on the lap, while the keyboard could still hold a mousepad. As said, just a crazy idea from me
EDIT: Also, since someone mentioned it: Maybe a small suggestions in addition to the mousepads: Maybe putting it a bit closer to the keyboard itself would make space for 2 dedicated mousebuttons? Just another small crazy idea by me, since I liked dedicated mousebuttons
But if you've got a decent mousepad like the macbook, then I'm OK with having no mousebuttons