It's a very valid question posed in this thread and everyone's going to have different opinions.
If you ask me, I think the 360 is a better IMMEDIATE purchase to get into the next level of consoles and does have a better online feature. HOWEVER, over the long run I think PS3 will be proven to be the superior model for gaming. It all depends on how you view the word "better". If I remember correctly Sony put out a statement saying they would be developing 180 new games within the year. If they can get their price down into 4xx level then they're gonna be fine. That will happen as they improve their supply and value chains IMHO.
To compare the consoles to a PC has gotta be a tough call for anyone to make. Yeah, PC's have alot more going on but the PC games have their advantages over consoles. I think updates and patches for PC games are nice to have, not to mention, if you like to tinker and optimize (like most people on this forum do) then you certainly have alot more options available to you.
Again, tough call to make. It has been for me - but I'm goin with a PC since I can always upgrade parts a couple years down the line.