I've used both Sonus DAS and SFX and both are excellent.
The SFX are a little smaller than the DAS pads but are more hydroscopic and tend to swell and keep the polish working a little longer.
From what others have said the Propel pads are similar to the Sonus DAS pads but cheaper.
I think most pads are good these days and you'll be happy with whatever you get once you learn their characteristics. :up