At a time when many people are considering a purchase of their first handgun for concealed carry, the most common question is, "What is the best gun for me".
I agree with a previous statement on this subject, "The biggest one you can safely handle". But really, all facts considered, that's not a very good answer to give a first time gun owner.
So the next question is always asked in our training classes. "What is best, .38 Special, 9mm, or .380, since they are all .38 thousands, right?
One instructor i heard made this comment, "A .380 is nice to have, if you don't have a gun". Although James Bond did quite well with it, huh?
So what does the group think about these three rounds, what's the best CCW round?
But Bond's preferred gun was a .25ACP Beretta. M ORDERED 007 to carry the Walther in the larger caliber, referring to the .25 as a "lady's gun". Bond could hit what he aimed at, though.
But then, are your basing your Bond history on the books (the original documents) or the movies?
Note also, that while James Bond was a fictional character, author Ian Fleming had first-hand experience in British Intelligence and commando operations, though it is unclear to me if he ever actually was an operative himself, he would have had close access to all manner of facts and research.
For that matter, are you basing your ballistic choices on works of fiction?
Rememer, Ian Fleming also wrote "Chitty chitty bang bang".
All kidding aside, I would expect Fleming's books to have some good advice. Sorting it out from the spectacular, inserted to sell books might be hard. Sorting out that which was added by the film-makers to sell tickets would be an exercise in futility.
So, here's my take on your question.
The .25 is easier to conceal. Bond was fit and a highly trained fighter bare-handed and with weapons. The kind of threat he was called upon to defend himself against was of a particular sort. What threat are you preparing against and what circumstances will you be carrying in? Those considerations would carry more weight than a simple "what gun"?
Automatics are easier to conceal, generally, than a revolver, but will require more practice to master the mechanics of operation. Revolvers are quite often more powerful and simpler to operate, but marksmanship is a little more difficult to master (double action trigger pull). So, the amount of practice you are willing to invest will matter to your choice.
The choice of "what is the best gun for me" most often comes down to trying a variety of guns and settling on the one that you operate most comfortably and accurately. Only time and first-hand experience and experimentation will tell you this.
The best we can do for you is to point out the pertinent questions for you to ask yourself as you live with a selection of guns.
How many gun experts have tried living with a particular gun for months only to discover that it isn't "the one" and traded for another.
Picking a gun for another person is as difficult as picking a spouse.
Lost Sheep
Note that the calibers you mention are not 38 hundredths of an inch in diameter. They are a little less than 36 hundredths. (9mm AND 380 Auto are .355 to .356" 38 Special is .357".). The diameter of the .38 Special CASE is .379" (close enough to .38" to call it even).
It's up to you to use them as best you can to find what works well for you. Go with the questions and statements that sound and feel the most 'high road'. 
