The Protector plays like a mini-atlas. It has a low slung should basaltic, which can hold an AC20, 2 missles and 3 lasers. I currently use
this build, and have quite a bit of fun in it.
However, the Orions are prone to losing their side torsos a fair bit, almost exactly like an Atlas, too. So if you like the feel of a fast, yet lightly armed Atlas, the Protector is a good choice.
Now the Misery is a freaking tank, like all stalkers, but it feels even more tanky when brawling (Which it can be quite good at). I currently use
this build on it. The Misery is the most unique stalker, as it is the only one with a ballistic hardpoint.
However, like all stalkers, it suffers from slow turning speeds, and twist speeds. Also, it is very prone to losing its side torsos, so that's why I but a LL in the CT and moved 2 to the right side, instead of having all of the weapons on the left side.
For me personally, since I have both mechs I'd go with the Misery. Both, however are good choices.