I have a Kraton with the mamba monster x, and a senton with the
max8. both esc's provide a HUGE upgrade over stock. at this point I can't see either one being "better" than the other. I would recommend getting whichever you can get for a better price, or whatever you feel more comfortable with. I know some people shy away from hobbywing because they are a "chinese knock off" I've had great luck with mine.
If you are going the castle route, I would recommend the mamba monster x over the mamba monster 2. simply due to the much more powerful
bec.