I prefer a touchscreen, the main advantage of having a touch screen phone is cosmetic. It is a great accessory to have and to be seen using. Touch screen mobiles can be small and slim and there are no bumps and bits, its all very sleek and smooth. Another pro is that a bigger screen fits in well with the multi-media functions on the latest mobiles. Watching video clips, whole films or TV programmes and looking at photographs is much better on the larger screen that covers the full area of the mobile. No space has to be wasted for the keypad.
For music, photographs and videos, you hardly need buttons and you only need camera buttons when you take a picture. It makes sense for these to appear on the screen, rather than to stick out all over the phone.
For texting and emailing, the touch screen does have some disadvantages (see later) but one of the good things is their flexibility. If you are used to typing on a keyboard, you can set the touch screen 'keypad' to be in the traditional QWERTY format but, if like me, you prefer to have the letters in ABD order, you can. Its just a matter of setting up the preferences.