Why PC gaming is better in terms of games, money savings and relibility.
PC gaming is better in terms of games, because there are more available on the PC then any console. You can buy games from the 90's on GoG, play free flash games in your browser, free ad-supported MMOs, and even play old console games on the PC (N64, etc).
PC gaming is better in terms of money savings for many reasons. Brand new 360/PS3 games that are $59.99 are $49.99 on the PC, and many times you can save even more through use of Steam sales, Ebay sellers, or hardware bonuses. Plus you can play literally a thousand free games, from Microsoft Spades to some Korean made MMO... how many free games are available on the 360 or PS3?
PC gaming is better in terms of reliability, because a PC has discrete parts that can be changed. If you get a RROD on the 360, you have to send the whole 360 in to be repaired. If your PC doesn't boot, and you have some tech experience, you have options (troubleshooting, switch out hardware, etc). In my case, both with a 360 and a PC, where the DVD drive failed - Open Tray error on the 360, didn't work on my PC... I had to send in my 360, and fixed my PC by ordering a DVD drive on NewEgg that arrived 5 days later.
These are superficial answers. Consoles are great, but PC gamers know a gaming PC is better, and never the two will agree.