There are many threads on LEOs seeking lights, perhaps you should consider checking through those to see what LEOs themselves are choosing.
Personally, the CL1H v4 looks great but as i am not an LEO, the light may not see the kind of use that an LEO light would. Also, for those on night shift, runtimes might be a factor unless they carry around spares.
Thinking on that, are there chargers which can use the 12v DC lighter socket to charge cells? THAT may be a good gift for an LEO, he can charge as he moves around.
As i personally do not own a Dereelight, i cannot comment but i do own Jetbeams and i can personally attest to their utility and durability (albeit from a civilian standpoint), i tend not to want to recommend the Jet III Military for LEOs (despite its name) as mode changing is done by twisting the bezel (head), which may be hard to do if the other hand is holding a gun.
I'd say go for the Jet III Pro ST (if still available) or the new Jet III Mk3, 1st mode on MAX to check out cars, perps, suspects, etc. 2nd mode on 50% if not so much light required. 3rd mode, strobe? minimum? the choices are all there. Switch to locator strobe to warn off vehicles in the event of a traffic accident. Fast strobe if entering a dwelling. All those choices are there in Jetbeam and their UI is really easy to get the hang of so that you can even program on the move.
Anyway, that's just my 2 cents worth.