What about the display? and the fact that we are comparing a 5.5inch to 5.2inch.
The screen is up to user preference tbh. The OP3's display size (5.5) is between the 950 (5.2) and 950XL (5.7), but only with a FHD quality (1080p), while the 950/XL both have a QHD (2560x1440) screen, meaning that the 950/XL would have superior screen sharpness and "Omph" effect, but since it's of a higher resolution, more battery would be consumed to power the screen. The OP3's screen would be less taxing on the battery, I think.
Also, from my own experience, the 950/XL's AMOLED screen would, in time, experience burn-ins. It is common on other flagship phones using AMOLED display, and can be prevented or reduced by doing some white screen sessions or something (preventing the phone's screen from turning off, and forcing the display to show a plain white background for a few hours or overnight). I'm not sure about the screen in OP3 tho. If it is AMOLED as well, than this problem would definitely occur with that as well.
So what I'm trying to say is that, the 950's screen is just beautiful to look at, but at the cost of battery power, as well as possible screen burn-ins. The OP3 has a less sharper display, which means a bit longer battery life, but if it's made of AMOLED as well, then it will experience burn-ins.