Have used both Brightsides and Toplac. Toplac goes on much easier with the roll and tip. It is not so susceptible to running, the thinning is not so crucial. If you have to use a one-part then I recommend Toplac. No runs and no brush marks.
With either one be sure to allow lots of setup time. It may appear dry but give it a couple of days before walking on it(my application was on cabin trunk and deck).