I almost always suggest a Double Action / Single Action (DA/SA) hammer fired system, especially for practical purposes. This system is extremely robust, reliable and very forgiving of handling negligence, which makes it very practical for new shooters, experienced shooters and for a pistol that you plan on depending on.

The DA is a long and heavy trigger pull, which is your first trigger pull, which basically means you have to intentionally decide to send that round or be outrageously negligent. After the first round, it gives a nice, very light single action trigger that is short and crisp. After you are done firing, you de cock it back into the double action (DA), which is the native state that it should be in when not being fired. The DA makes it incredibly unlikely that you will have an unintended discharge while holstering the firearm as well, and if you place your thumb over the hammer while holstering, you can feel if anything is interacting with the trigger when holstering, and make it damn near impossible for the gun to fire.

I recently switched to a Beretta 92G from a SIG P226 legion that I carry both as an EDC and duty firearm. When I carried the P226, I was in a very stressful situation where the decision between shooting a suspect or not was in the air. I made the decision that lethal force was clearly applicable, but not quite necessary at that point in time. Well, shortly after I made that decision, the suspect continued to rapidly amp up the situation, and I found that my subconscious reactions had me instinctively place my finger on the trigger, which I immediately noticed when I started to feel that heavy trigger and saw the hammer start to draw back.

I was well within my rights to use lethal force; however, the DA trigger press took me back into more of a thinking state, allowing me to more consciously choose to not discharge my weapon at that time. Keep in mind, this is an instinctual response, especially the more intense a situation gets, and most people don't even register their finger has actually entered the trigger guard or even that the trigger is starting to be pulled at all or until it's already been done.

Long story short, this will happen to anyone, regardless of training when a certain level of stress is introduced, especially if it is rapidly introduced in a very short time frame. That long and heavy trigger press had a key role in making me choose different tactics, which lead to the suspect being uninjured and taken into custody. The DA/SA isn't the most popular thing nowadays, but it is the best option in my opinion and it is making a comeback, and for many good reasons. It does not matter if you are a beginner or an expert shooter, DA/SA is superior for almost any environment and for almost anyone. Learn the double action pull, learn the single action pull, learn the DA to SA transition and learn how to de cock after your firing sequence. All of which can be learned in less than 200 rounds of intentional practice.

Look at Beretta, HK, SIG, CZ and Sphinx (I'm sure there are others) if you are interested in checking them out. The bigger the gun the easier it is to shoot and the harder it is to conceal. I don't typically recommend revolvers because of multiple reasons. I would get something between compact and full size options. With a proper belt and holster setup, you can carry a full sized gun comfortably and discreetly, unless you wear skin tight clothing, then it would be probably be difficult. The bigger gun you get, the more likely you are going to practice with it because it will actually be fun to shoot. Small guns are very rarely enjoyable to shoot. My full size Beretta 92G with a Surefire X300T is with me for \~23 hours a day. When I'm not at work, it is carried in a Tier 1 AIWB holster with an extra magazine attached.