hi
I would like to know which system is better for running unreal engine 4,I would go with imac because its cheaper than the mac pro but I am afraid it gets too and I would go with a mac pro because I heard it stays really cool but its very expensive.
thanks
You are better off getting a PC for Unreal engine 4. Cheaper and driver less issues.
Mac Pro instead of imac
With the amount of money you are going to spend for a mac you can build a PC that runs circles around it.
My personal opinion is that if you want to use unreal you should buy a very powerful PC (16gb ram,r9 290 or a 970-980 and either an FX 8350 that you can overclock to 4.6 ghz or an I7 + SSD)
Anything less than that you will have a really bad time later on when your game starts to get bigger and bigger.
My system with the above performance is struggling to maintain a frame rate above 20fps when i have my main character blueprint open.Imagine what will happen if you buy an Imac! 
thanks for all the answers.
do you think I have to upgrade?
I have a amd fx 8320
r9 270 oc
12gb ram
thanks
No you are more than fine to do a lot. At some point a bit more ram but you can do high end things with that set up.
thank you
