I use the Prestone, mixed 40/60 because (a) the manual says so, (b) more water should cool slightly better [albeit with a slightly lower boiling point than 50/50], and (c) the concentrate is cheaper, and I'm a cheapskate.
For various maintenance reasons (first scheduled maintenance, then water pump, then water pump again....) I've changed my coolant about three times in the last year. One of those times I figured I'd do a flush with Prestone radiator cleaner as well; what the heck. Rinsed it out several times, once or twice with hose water, then once or twice with distilled, then filled with 40/60.