Yugo,
Your question doesn't have a short, easy answer. Climate and the daily apparel you wear will have a direct impact on what you can easily and comfortably conceal.
Most people live in climates that are somewhat seasonal and therefore require concealment in winter, which is easy due to heavy and layered clothing, and the summer when clothing is thinner and concealment is more difficult.
If you are going to buy only one pistol for CCW, which is good from a familiarity standpoint, you must consider your most difficult time to carry and buy accordingly.
That's why some have recommended the G23 or G27.
If in an office environment, where a tucked shirt is required, deep concealment will likely be required. Holsters are made by Galco and others that allow you to carry IWB(inside the waistband) and still tuck the shirt over the pistol. For this condition, I would also recommend the G27.
If you can where a vest, jacket, or untucked shirt, you can get good holsters that can carry any of the ones mentioned.
One word of advice- dont buy a well-made $500 pistol and try to carry in a $10 holster. Your holster needs to be of similar quality to serve the needed purpose.
Consider all the factors well, read and study to make an educated choice, and you should do fine. You also may find you need more than one holster for different occasions.
Good Luck,
Dave
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"Now is truly the time to stand up for your rights, or sit down in subjection"