This is an important point. The B&W function on your camera will give you the camera manufacturers rendition of what B&W should look like. Similarly if you use PS or another software and click "convert to B&W" then you will get the programmers idea of what B&W looks like - and this is often an emulation of a standard old B&W film like Kodak Tri X Pan.
If that's what you want then OK
adjusting in photoshop would give you more versatility
This is elluding to the fact that sophisticated software like PS allows an almost limitless number of B&W renditions of the same color image by mixing different amounts of red/green/blue into a finished B&W image ... this is not "adding a B&W effect" - but rendering the data in the file into a grey scaled gamut. See example below:
Notice how different all of these are - it is not just the exposure; look at the lips compared to the skin color ... no one of these is "correct" and the others wrong; it's entirely a creative choice
In short - shoot color (RAW)
Sometimes you're the windshield; sometimes you're the bug.
"chance" favours the prepared mind ...