6.5" circular saws are generally a waste. The circular saw is the most versatile and important of all power tools IMO, and that small size drastically reduces its efficiency. Definitely go with 7 1/4. I've got a Ryobi that has been my primary circ for the past few years that I've been pretty impressed with. it has good accuracy with the bevel markings and strong power. It is the first one I've had with a laser sight ... Not really a necessity for a circ but a nice additional feature for long rips. I've also got a Black & Decker that has more power, but I have a bad habit of throwing/dropping the saw on the ground when I am done with a cut, and after a few years it knocked the blade wheel out of alignment. The Ryobi has held up better to that. So the B&D i only use for plywood or other relatively thin boards where the slant does not affect the cut. I had a Craftsman for a bit but the motor burned out after about a year.