What technology used in cell-phones determines how good the internet service will be?

I own a Nokia N75, and the internet is pretty good, except with things like youtube(the picture is blurry and sometimes slow). I want to upgrade to a better cell phone with a better internet connection but I don't know how to pick one. Can anyone help?What technology used in cell-phones determines how good the internet service will be?
the type of connection (like EDGE or 3G) and the network type (GSM or CDMA AND EVDO) phones with 3G are always faster and EVDO and CDMA are typically faster than GSM but not always