Should i get Minecraft for PC or PS3?

PC, it's way in front of console Minecraft with like objects in the game and stuff.
Also PC you can join servers.
You can download mods.
On PC there's a lot lot lot more texture packs.

For the best experience go for the PC version. The world generate is unlimited whereas on console you can only go so far. PC version is far more updated with horses, mules, carpets and much more. The multiplayer on PC is far better as you can join big servers and play mini games such as Spleeg, one in the chamber and the herobrine. And not forgetting the best thing about PC minecraft, the mods! So many mods to customise your minecraft from different mobs to new items such as working machines.

The PS3 version is simpler, especially for beginners, with the tutorial level and the simplified crafting system. But, you're stuck with only official mods that cost money, and a limited world size.

The PC version has unlimited worlds, but you have to do more work when you're crafting -- but there's more you can do too. There's also more mods and more other people to play with.

PC's better, but PS3 (or 360) is good for just general screwing around though it's easy to outgrow.