Whats the best police trade in gun to buy?

so i hear its a hit or miss on the police trade in guns i talked to this gun shop and they said they inspect all the police trade in guns that come into the shop before selling i was wondering what is a safe bet to buy on a police trade in gun glock sig, hk,cz ruger what pistol would be most likely to work the best being used just in general i know it varies gun to gun but just in general what would last the longest used? thanks for any answeres