Some like high-tech typefaces so clients conclude they are a technological savvy firm. Personally, I like a letterhead that is quiet and understated. One trend among law firms is to put forth a corporate image, like a Fortune 500 company. Personally, I prefer law firm stationery to have the appearance I expect of a law firm, and not look like a company that sells toothpaste or oatmeal. Another consideration is kerning, the horizontal space between the letters in each word.
Some designers increase the space between the letters in hopes of creating an elegant, upscale look.
But when designers add horizontal space, often they lose readability and create a design that appears awkward. In marketing, always look first for readability. Everything else is secondary. Stay away from fancy scripts and any font that is hard to read. People don't like challenges.