Makita makes a good circular saw, I think the model number is 5007FK. I've owned this saw for 3 years, and have been very happy with it. It has plenty of power, the adjustemnets for depth and bevel angle are very easy, and to me the visibility to the front tip of the blade is a little better on this saw than some the others in this class. It comes with a good quality blade as well, and an edge guide, at least when I bought mine it did.
Top of the line in circular saws generally means a worm drive saw like the Skil model 77 or Makita hypoid saws. Those saws are high torque, but heavier to handle. If you're cutting framing lumber all day long, you might consider one of those, but for plywood, or 3/4" material, they may be overkill.
Other brands I'd look at...? Milwaukee, Bosch, Dewalt, Porter Cable... they all make good tools. I would stay away from anything at the low end like B&D, Craftsman, Ryobi, Rigid.
Also, consider a long edge guide like a clamp-n-guide to go with your circular saw. I think you'll find it very useful to make straight and accurate cuts.