I feel like they're both honestly almost exactly the same. Rangefinder obviously increases range and accuracy/aim assist is built into the range stat. Plus it helps dealing with dmg drop off and accuracy/aim assist drop off. Maybe not by a whole lot, but atleast it helps. Hidden Hand only increases base aim assist by 10-15%. I forgot exactly what it is now since the nerf it was given. For me, aim assist doesn't really help much with sidearms. Definitely not enough to where I wouldn't consider the vendor roll as a god roll. But hey, whatever works for you man.