To bob, or not to bob, that is the question... I prefer hammerless or bobbed hammers due to the advantage of being able to draw from a pocket. In general, a bobbed hammer requires you to shoot double action only, and my 65 is set up from the factory with a bobbed hammer / dao. My model 10 has the hammer bobbed, but is not dao and requires a gentle pull of the trigger in order to get the hammer back enough to get a thumb on it to cock it. Needless to say, it would never be cocked in a threat situation. Some people who have trouble shooting double action, such as those who are getting up there in years or with a physical disability may need to cock a hammer in order to shoot. Generally speaking though, cocking a revolver when faced with a threat has some drawbacks. It takes time, it makes it much easier to discharge the gun unintentionally, and it requires lowering the hammer on a loaded cylinder to make the gun safe.. If you are in a stress (fight or flight) situation, the adrenaline dump will have sent your fine motor controls out to lunch for awhile, and trying to drop that hammer without hearing a loud noise can be problematic with some folks.
It comes down to personal preference and safe practice with whatever gun you decide to use.