Well, that choice is completely up to the user's discretion. If you enjoy games specifically designed for Xbox only, then the console system would be the choice. If its concerning graphics, online gameplay, and gaming experience, PC would be the better option.
Here are the generic specs on the MIcrosoft Xbox360 gutted and benchmarked:
Processor: IBM tri core cpu @3.2Ghz
RAM: 512mb DDr2
GPU: ATi 500mhz core clock w/512mb gddr2 ram
Storage: 20,60,120,250gb HDD clocked at 7,200rpms @ 8mb cache memory
Now you also have to look at what Microsoft does NOT tell you about its Console
-Does not burn multimedia files
-Additional charge per month for Live Subscription for online gaming
-Infamous defects such as the Red Rings of Death or RRODS
-GPU is way outdated, same with Shader Model
-Batteries on Wireless accessories dont last long
-Cannot surf the internet
-Modifying in anyway voids Microsoft's 2 year warranty
-Some games are not ful 1920X1080i supported
So, if your not concerned about money issues, the PC would be a better choice. If you want a simple "Plug and Play" features, Xbox would be the choice.