New Computer Recommendation?

Hi everyone!

I have been toying with the idea of getting a new desktop computer for my bedroom. I haven't decided which kind I am going to get but I am leaning towards a new 2013 27 inch iMac. The reason being is that I use my iPad 2 as pretty much my sole computing device right now and it has been serving it's purpose pretty well for the most part. I figure that Microsoft Windows 8.1 is a shoddy OS and I can always run Parallels or Bootcamp if I need to run one of those programs. What are people's opinions on iMacs? I was even looking at a new Mac Pro since most reviews say you get ALOT for your money with the dual GPUs. However, I don't think for all intense and purposes, I will need that much raw processing power for basic word processing, e-mail, browsing of the Internet etc. Again, what are your opinions? What specs would you stick with? I am looking at forgoing a platter hard drive in exchange for a 500Gb or 256Gb solid state drive since I like speedy boot ups on my iPad. Maybe 8gb of ram to start since they are upgradable I can't see more than 16gb of ram in the future. I haven't decided if I will game that much on it yet so I don't know about video cards or whether the 1gb NVIDIA they include in the base 27 inch will be enough. Going back to hard drive space, I am thinking about putting a 4tb NAS on my home network to store most of my larger files like music and photos. Do you think 4tb is way too much to get? I am probably only using 500gb of my hard disk right now for music but wish to build my library eventually...

I have also been looking at gaming rigs from a company called Digital Storm but they are quite expensive and don't come with 4k monitors in their $3,000 price range for a solid i7 system with 16gb of memory. Hmm....there are just too many things to decide upon....