Wider, rather than narrower, is the current men's collar trend. The medium dress collar is the all-familiar one. It's like the 2-button jacket: always in style, never out. The more modern way to go is wider- basic wide, cutaway, english spread, the names vary but they all refer to a wider collar.
Face shape & collar recommendations:
Regardless of trends your best collar spread is sometimes related to your physical features. If you are heavier or have a circular face wide spread collars will not do you justice. Stick with the basic medium spread. Guys with a narrower or square face can pull off many collar spreads,
Specific collar tips:
Narrow collars: unless you are doing a pin collar (which is very fashion forward) the narrow spread collars are not very popular. Most of you should stay away from the narrow collars- it will likely look outdated rather than hip.
Button down collars: the biggest collar faux pas happens here. When you have a suit on, or a silk tie with a sport coat/dress pants, do not wear a button down collar. If you do, at least have it be a hidden button down. If you can see the buttons, consider it casual. You can't take a casual shirt style and dress it with a three piece suit. It just doesn't work. If you want to wear the visible button down collar, do so with business casual to street style and if you want to wear a tie, wear a knit one.