Step 1: Find out what your dept. considers "OK" Regulations and climate vary.
Step 2: Figure out what you want it to do - will this be primarily a tool, backup weapon, or a mix.
Step 3: Try to find a good brick-and-mortar store where you can try out a few models. Spyderco has lots of blades that are similar, but can feel very different - Police, Military, Endura, for example. Actually holding them will let you make a better choice than otherwise. If you narrow it down to a few models, a good store should be able to order them and let you experiment.
My personal opinions -
Backup:
Consider a small fixed blade. If you're in a situation bad enough when you can't use something else and can't regroup elsewhere, you don't need to be screwing with an opening mechanism (including autos) or a lock that might fail. Otherwise -
Military - good all-around popular performer. Easy to find in G10. Tip is thicker than police
Police - large blade in a small package.
Endura - workhorse, easily replaced, slightly smaller than Military/Police if you need to work around a length restriction
(ATR) - Step up in tip strength, price. Different handle shape, and Ti handle will cut weight
(Gunting) - useful if OK with your department, and you want to spend time learning the ramp. Several die-hard gunting fans on this forum are also LEOs
Never used a Civillian, so can't speak on it. The thin tip and inability to stab would make me nervous using this as a last-ditch option.
Benchmade has some good stuff that competes directly with these Spidies. I have an AFCK (which was originally derived from the Police, I believe) Axis lock is very easy to open and close. I think Spyderco G10 handles have more grip. Handle shape, with the finger choil, is a bit different and keeps your hand well back from the blade. Don't like the beveled hole on the Benchmade - it looks and feels more finished, but the Spydie hole gives better purchase for opening.
Tools - this is the direction I would personally go in. You'll use a knife more in this capacity, and a serrated model can still make pretty devastating slashes through nearly all clothing.
1. Assist - if the finger-groved handle is comfy, it's pretty hard to beat, since it was designed with you in mind.
2. D'Allara or Rescue - nearly identical function, buy the one that feels better. Ball bearing lock takes a bit of getting used to, and may be more difficult to operate in extreme conditions (particularly cold, or with gloves).
Good luck! Stay safe!