The first thing I want to know about a handgun is the type of action. I don't like Single Action Only guns...just a preference.
And, I notice a lot of people looking to purchase guns don't think about how the gun will be operated, whether you can dry fire the gun easily, how hard/easy the trigger pull will be, and everything associated with the operation. This poll is not intended to measure whether a particular type of action is a better firing pistol, but more what people PREFER to shoot and operate.

Here is how I define them:

Double-Action/Single-Action(DA/SA): Whether there is a bullet in the chamber or not, when you pull the trigger and the safety is off, the hammer will pull back and drop in Double Action mode. If a bullet was in the chamber it will fire and the action will eject the casing and feed the next round and cock the hammer so it is ready for single action trigger mode. When pulling the trigger again it will be in Single Action mode, and less force will be required to release the hammer and fire the round. Single Action mode will continue for each round until all rounds are gone. This type of trigger action means it will have "double-strike" capability so if a round fails to fire, the trigger can be pulled again in DA mode and fire the round (if the round is good). Guns with decockers will return the trigger to be capable of being pulled in DA mode. This also means dry-fire exercises can be done in DA mode without cocking the hammer and in SA mode by cocking the gun. Examples: Ruger P95, Beretta PX4 DA/SA, Cz 75B, Bersa Thunder.

Double-Action Only(DAO) Double Strike(DS): Whether there is a bullet in the chamber or not, when you pull the trigger and the safety is off, the hammer will pull back and drop in Double Action mode. If a bullet was in the chamber it will fire and the action will eject the casing and feed the next round. When pulling the trigger again it will perform the exact same trigger/action function and with the same trigger pull. This type of trigger action means it will have "double-strike" capability so if a round fails to fire, the trigger can be pulled again and fire the round (if the round is good). This also means dry-fire exercises can be done in DA mode. Safety's are available but decockers don't make sense in DAO/DS pistols. Many Law Enforcement Agencies require this kind of trigger because the officer pulls the trigger longer and harder and gets them to think through the shoot/noshoot decision, and provides better training because there is no difference between trigger modes. Examples: S&W Bodyguard 380, Keltec PF-9 and P-11, Sig P250.

DAO No DS (I actually think this is Single Action Only): If the trigger was not previously pulled, whether there is a bullet in the chamber or not, when you pull the trigger and the safety is off, the hammer will pull back and drop in Double Action mode. If a bullet was in the chamber it will fire and the action will eject the casing and feed the next round. If the round didn't fire or there was no round in the chamber, the trigger will not operate until the slide is cycled to reset the trigger. This type of trigger action does NOT have "double-strike" capability so if a round fails to fire, the trigger CANNOT be pulled again and fire the round. This also means dry-fire exercises CANNOT be done without recycling the slide. Examples: Ruger LC9, Sig P290.

Striker-Fired Half-Cock: If the trigger was not previously pulled, whether there is a bullet in the chamber or not, the striker will have been cocked half-way, so when you pull the trigger and the safety is off, the striker will pull back the remaining distance and release. If a bullet was in the chamber it will fire and the action will eject the casing and feed the next round and halfway cock the striker. If the round didn't fire or there was no round in the chamber, the trigger will not operate until the slide is cycled to reset the striker. This type of trigger action does NOT have "double-strike" capability so if a round fails to fire, the trigger CANNOT be pulled again and fire the round. This also means dry-fire exercises CANNOT be done without recycling the slide. A decocker may be available, but if used will require you to cycle the slide to recock the striker or eject the round in the chamber. Examples: Glocks, Most Kahrs, Walther PPS/P99.

Striker-Fired SAO, although some mfg call it DAO(Operationally the same as DAO/NoDS): If the trigger was not previously pulled, whether there is a bullet in the chamber or not, the striker was previously fully cocked, so when you pull the trigger and the safety is off, the striker will be released. If a bullet was in the chamber it will fire and the action will eject the casing and feed the next round and fully cock the striker. If the round didn't fire or there was no round in the chamber, the trigger will not operate until the slide is cycled to reset the striker. This type of trigger action does NOT have "double-strike" capability so if a round fails to fire, the trigger CANNOT be pulled again and fire the round. This also means dry-fire exercises CANNOT be done without recycling the slide. Decockers make sense, but require the slide to eject the round in the chamber. Examples: Springfield XD's.

Striker-Fired DAO (Operationally the same as DAO/DS): Whether there is a bullet in the chamber or not, when you pull the trigger and the safety is off, the striker will be cocked and then released. If a bullet was in the chamber it will fire and the action will eject the casing and feed the next round but will not cock the striker. If the round didn't fire or there was no round in the chamber, the trigger will operate in the exact same manner in DA mode, cocking the striker and releasing. This type of trigger action DOES have "double-strike" capability so if a round fails to fire, the trigger CAN be pulled again and fire the round. This also means dry-fire exercises can be done without recycling the slide. Decockers don't make sense since there is a full DAO action every time the trigger is pulled. Examples: I couldn't confirm any, but I believe some of the H&K's and Sig's have this feature.

Single Action Only (SAO) Hammer (1911 Modes): Whether there is a bullet in the chamber or not, the trigger will not operate until the hammer is manually cocked or the slide is pulled back to cock the hammer. The trigger only operates in Single Action mode, releasing the hammer. If a bullet was in the chamber it will fire and the action will eject the casing and feed the next round and cock the hammer so it is ready for single action trigger mode again. When pulling the trigger again it will be in Single Action mode, and continues for each round until all rounds are gone. This type of trigger action means it will NOT have "double-strike" capability so if a round fails to fire, the trigger CANNOT be pulled again. This also means dry-fire exercises CANNOT be done without cocking the hammer or cycling the slide. All modern SAO pistols have safety's and the normal way to operate the pistol is to load the magazine, and rack the slide to load a round, and then turn the safety ON. To fire the pistol, just set Safety to OFF and pull the trigger. Most pistols do not have decockers which means there is no way to safely decock the pistol unless you remove the magazine and rack the slide ejecting the round. (Now maybe you see why I don't like SAO pistols) Examples: 1911 pistols, Sig P238.

Please vote!