When you are trying gloves on don't just slip them on and say, "These will do." Manipulate your weapon, radio, handcuffs, grab the steering wheel, etc., while wearing them.
It might sound very simple, but how the gloves fit when you are operating your gear is not the same as how they feel when just slipping them on. You don't want to find out they're loose or uncomfortably snug halfway through your shift. Make sure the gloves' function is as good as their looks.
Function
Another consideration that will sound overly simple is, What are the gloves for? Are these gloves to keep your hands warm, dry, or to protect them from punctures? Do you need the gloves to serve multiple functions? Are you operating in harsh weather conditions? Are you wearing the gloves as liners under mittens such as those worn by the military for extreme winter conditions?
When it comes to keeping your hands warm in extreme cold, you will give up dexterity. Sadly, 99 times out of 100 truly warm gloves do not lend themselves to allowing for touch/feel dexterity. Insulation is simply bulky. Because of this, in very cold weather I am a fan of shooters' mittens. You can simply flip back the finger area of the mitten so you can write, operate your weapon, and do other things for which you must be able to "feel" your way.