I always use 16oz for sparring, and it seems universally the norm for everyone I've ever sparred, or seen spar, even the lighter guys. That's pretty much the large majority of what you'll find laying around in the gym, and hell in my house.
14oz up MW are fine, but it is sparring so what is the point of not wearing 16's? Above 150? You need 16oz for your punchers. HW should probably use 16's and up.
i use 16s always have my trainer is more bothered about the sort padding they have and protection for your hands and you sparring partner
We should all be using 9 oz and sparring with 18 oz for safety and speed/power. And slipping in controlled sparring sessions with 9 oz. Floyd Mayweather style. Not an unofficial fight with two pairs of 9 oz.