Honestly I haven't noticed a huge difference. But I'm not overly obsessed with that kind of thing, so it's no big deal. I just happened to find the Advanced AV Pack for XBOX clearanced at $15 so I bought it. I didn't even use it until I got some more systems and wanted to use the System Selector for other things.
Also, just wanted to get back to something x2 asked earlier:
So I guess my question for anybody with all 3 is, how do you keep them all organized? And by organized I mean how do you pick and choose what to buy/play???
Here's my advice on that:
Demos are your friend! 
If there's a game I'm kind of interested in but not totally sure about, I try to get a demo of it. I have to say that with my connections I'm able to get more demos than the average person, but there's plenty available for those that don't have connections. For example, JamPacks for the PS2 offer lots of demos (the most recent one has 12 playable demos!

) You can also get demos for the PS2 in the Official Playstation Magazine. For XBOX, there's always the demos offered in OXM. Gamecube is the only one that is hard to get demos for, period. If you're lucky, the stores that have Gamecube kiosks near you might actually have the most recent demo, but that's always hit or miss. Right now the current kiosk demo has Paper Mario 2, Donkey Konga, Pikmin 2, and Mario Pinball demos.