What computer should I choose?

Objective of the computer:
- Play games such as World of Warcraft, DayZ, GMod, Minecraft, and so on (not too heavy, I suppose).
- Photoshop/Flash/After Effects projects (I have 8 gigs of RAM and currently After Effects alone wastes me 4 gigs of RAM alone)
- Game Development (using cry engine 3/unreal engine 4/autodesk, etc)

Which is the best?

LENOVO Z50 £699
Intel® i7-4510U Processor
- Dual-core
- 2 GHz / 3.1 GHz with Turbo Boost
- 4 MB cache
Memory: 16 GB
Graphics: NVIDIA GeForce 840M
Hard drive: 1 TB SSHD

OR

HP ENVY 17-k251na for £799
Intel® i7-5500U Processor
- Dual-core
- 2.4 GHz
- 4 MB cache
Memory: 12 GB
Graphics: NVIDIA® GeForce® GTX 850M
Hard drive: 1 TB & 8 GB SSD

OR

LENOVO Y50 £899
Intel® i7-4710HQ Processor
- Quad-core
- 2.5 GHz / 3.5 GHz with TurboBoost
- 6 MB cache
Memory: 16 GB
Graphics: NVIDIA® GeForce® GTX 860M
Hard drive: 1 TB SSHD

My personal comment: I have never used Lenovo, but I have tried an HP Pavilion and it broke right away when it fell on the floor for the first time (screen frame fell off etc!) from a really small distance (about 20/30cm). I'm looking for full performance. The Lenovo looks great but I'm not sure about the graphics card, because I know GTX is better than GT and GT is better than just GeForce, right?
I realize the third lenovo is the best in performance, but the price is kind of worrying, so I'm asking for an opinion on that too.

So, which one should I choose?

Although the third one is best, but you've said that it's too costly.Purchase HP Envy as it has GeForce GTX 850M and more powerful cpu, suitable for intensive applications like CryEngine, Unity etc.
The only thing is that it has only 8GB SSD cache, which will apparently make your PC slight slower than Lenovo z50. Its just because of the HDD and has nothing to do with the kind of performance you need in game development.

The first one