Since I have used both Sunway Photo & RRS - I can offer some concrete pros/cons.
IMO - RRS is better. Why - the quality of the Sunway is lower.
- to get the movement of the ball to work well it comes packed with grease (on the ones I had). They do this because the machining is subpar of the two mating surfaces, and they want it to feel smooth.
- the internal part that connects the ball and socket in the Sunway head I was using broke as well.
I have used an Anvil 30 for years. Because of the reversed ball socket arrangement it self cleans.
- it doesn't require grease to make it smooth, it is just machined well.
- the RRS mechanism (lever) stays in place with varying amounts of tension
There really is something to be said for paying for better quality. The Sunway is less expensive, and there is a reason why they are less expensive. However, that doesn't mean you can't make them work for what you want to use them for, just don't fool yourself into thinking your getting RRS Anvil-30 for a significant discount.