Porter Cable all the way! I ordered mine off of eBay, and got a sweet ass pad kit from Autogeek.net. That place is awesome. I got a pad kit with all color pads, some Natty's blue paste wax, and a sweet Pinnacle advanced swirl remover kit. It's just about everything I will ever need. I do try other toppers and waxes every now and again from them. I highly recommend shopping there, as well as checking out autopia.org. That place is pretty cool too.
If you want something to use all the time I agree the porter cable is good. If you want a pro detailer rotary buffer get the dewalt 849. It has an rpm labeled dial instead of just useless numbers. It has the right feel and will last just about forever.
I was a detailer a few years ago and I wouldn't use anything but the dewalt on a full detail. However, on my own cars it would be too much to use all the time. I'd use the porter cable for that.