PlayStation 2 is my first choice. Right now, they have an awesome library of games. Metal Gear, Devil Man Cry, Silent Hill 2, Final Fantasy X, Gran Turismo 2, SSX Tricky... the list goes on.
The game I can't wait for is Final Fantasy XI Online. If you thought Phantasy Star Online was good, wait till this game comes out and kick A**
I think the X-Box is going to dominant the online console gaming industry down the line but right now the PS2 just has better games. If you are looking for longterm...meaning you are going to buy one system and nothing else for years.... X-box has the superor hardware and support. If you just want to fill your gaming appetite right now, PS2 is your choice.