The GoPro is better as far as specs go and I have a story about the Actionpro that you may find helpful. I work in a shop that sells GoPro's and we have a regular customer that has been coming in, looking at the accessories for the last couple of weeks. Last week he asked me about the cameras and I told him all about them. He then asked if I had heard of the Actionpro's as he had just picked one up for about half the cost of a H3B and was wondering if the accessories would work with his camera. I told him I hadn't heard of the and wasn't sure but if he wanted to bring it in we could give it a go with one of the chest mounts or something similar and see if it worked. Long story short; No dice. The clips and even the mounting screw all looked nearly identical to GoPro's but they were just slightly smaller and there was no way they would work together.
There are plenty of other good cameras out there that are reasonably priced and have good optics but when you get to mounts, lights, filters and everything else, GoPro has the market cornered. Company's everywhere are falling over themselves in order to make GoPro compatible products. You don't see that with any other camera out there that falls into the POV action sports cam category.