Where are you getting your info?
First although in regular day to day driving the benefits of synthetic oil may not be largly noticable the margin does grow larger in cars and engines that are used more agressively, such as racing. Now I don't know how everybody else drives but I myself have to step on my mustang every now and then just for kicks. And as for leaks and brands, I switched from regular quaker state to full synthetic Mobil 1 and have had no leaks what so ever, and my car has 226000 miles on it. Now if you switch from syn to reg oil the reg oil can tend to build up gummy deposits inside your engine which isn't good. Now for the brands, a privately owned lub company in my area did research on oils nationwide and found Mobil 1 to be the top syn oil on the market and #2 believe it or not is Wal-mart's Super-Tech Full-syn oil. Hope any of this helps if not thats fine to, but I will not use anything other than Mobil 1 in my vehicles because since I switched my cars have been getting 2-3 mpg better mileage and the oil has been cleaner between changes which means less work for the engine over time.