Dry Chem is a corrosive agent and will damage surfaces where it alights, even if the fire was nowhere near it. Not great if you have a lot of electronics. Cleanup afterwards is messy, so it's not really something you want to be using for a small trashcan fire.
Neither CO2 nor Dry Chem have the penetrating power on wood that a water extinguisher has. Halon was definitely the thing to have, as it worked by displacing the oxygen effectively killing the fire. A pity that it turned out to be bad for the Ozone Layer and also produced toxic fumes at extreme temperatures.
You might want to consider having two extinguishers:
1. A water extinguisher for use on Class A fires (wood, paper, ordinary combustibles). Minimal mess, easy cleanup for the small fires. Just be aware that it must not be used on any fires involving liquids, like pools of oil or gas, as it will just splash the liquid and the fire into a larger area.
2. A CO2 (my preference) or Dry Chem extinguisher for Class B (Flammable Liquids, etc) fires.