Do your research and decide whats best for you. While some opinions on here will be helpful,some,won't. It's alot of money to spend. A PC would be better if you want better graphics,mods etc,but PC gaming isn't always a bed of roses,you can have problems or alot of frustation with it,but when everything works fine,it is in my opinion the better experience. I used to play games on PC a long time ago,but i'm happy with my 360. Just because i have a 360 though,doesn't mean i should tell you to spend money on that and then get a great TV for it,it's alot of hard earned cash.Do your research and look at the pro's and cons of each. You need to know the up and down sides of each platform. People saying buy this because i think it's better because they are defending their choice is not good advice. Not everyone will do that here though,but some will. I would feel a little guilty giving advice like that,when that much money is involved.
Like i said look at all your options and take it from there.
I would be tempted to buy a PC with that money. But like i said, PC gaming can require alot of patience sometimes,and you will get conflicts or problems somewhere along the lines. If you are comfortable with using PC's and have patience when needed it could be a better choice,but that depends on you. PC user's on this forum should give honest advice,both the positives and negatives of PC gaming. All in all,look into it properly,don't just go of this forum alone. That's my advice.