I want to know if not having a USB port on the Sony cams is a problem?-- All hard disk drive (HDD) camcorders use USB to transfer video to the computer.

Is the touch screen?-- Personally, I think the touchscreen is fine. It might be too hard to operate for large hands, but it gets rid of a lot of buttons on the camcorders case which helps. It works well in sunlight as well.

About the four you listed:

I do not have much experience with the Panasonic HDD camcorders so I cannot comment on video quality or ease of use; the latter depends on the user. One thing I do not like about the SR200 or SR300 is that they are missing a viewfinder. I use the viewfinder sometimes when I'm running low on battery; it gives me an extra 15-20 minutes of recording. With the SR200 and 300, you must use the LCD which consumes a lot more power. Based solely on video quality, the SR300 wins. The best bang for your buck would probably be the SR200. I'll let others comment on the Panasonics; sorry about that.

Hope this helped a bit.