It depends on the organisation and customers. A B2B is totally different to a B2C. Is it a youth market. Does the organisation's strategy geared towards value or price.

Humans read words as images, typography is about communicating a voice. AGDA has a wealth of communication designers that can guide you. Of course, if one doesn't value their business, just head towards the army of decorators on crowd sourcing sites. Then cry about life being unfair that your smarter competitors are killing your business.

John, how long is a piece of string?

Typography says a lot about you and your business.

What fonts are the most or least professional depends solely on the nature of your business and the market you operate within. There is no definitive font but there are many styles that can be perceived as inappropriate.

John

Your question reminds me of the Desert Island typography game. You can only take 10 fonts with you, so list your go-to typefaces to cover every conceivable written situation. Yes, it's fun and interesting, but no, it can never be definitive.

What the font "says" about the business depends on whether it has been selected for corporate/internal use and is therefore standardised across multiple media, or for a piece of promotion. For the latter, the only consideration is whether the type appropriately conveys the message to the market.

In every case, font choice is down to the skill of the designer, and how successful S/He is in creating the desired impression in the reader.

Font choice is completely subjective. One man's Helvetica is another man's Comic Sans. What I consider professional may not carry the same connotation with others.

In the most basic sense, most typographers and designers I know generally accept that serifs can traditionally be invested with impressions of: conservatism, elegance, legibility, high quality etc. And sans are often associated with: modernism, clarity, adaptability, etc.

Equally, the reverse can be true, depending who you're talking to.

I have a short list of personal Desert Island favourites, but none are selected on the basis of "professional appearance." All are selected for their appropriateness to the project. Horses for courses.

John,

I'll give you some insights from a designer's perspective (I do graphic, branding, web and user experience just to name some). Why is mentioning those disciplines important? They all factor into typography choices and ideas.

First you must think about your format (or media). Fonts that look great on paper do not always translate well to online consumption.

Unless a font is selected for artwork (poster, flyer, or a logo) you want to minimize the strain you are putting on your audience (e.g. would you want to read an entire book printed in cursive or calligraphy? No, the strain would hurt your eyes).

There are literally 1000's of fonts you could choose from, however, you should always keep your audience and the amount of words in mind.

Popular fonts online are Roboto (Android), Ubuntu, Helvetica Neue and San Francisco (iOS) as well as classic Helvetica and Arial.

In my opinion fonts that should always be avoided are (Comic Sans, Papyrus and Stencil). These fonts are typically overused, hard to read and just plain obnoxious.

Good fonts for printed material are Verdana, Univers, Gill Sans and Courier New. These are easier to read printed out than many other fonts.

Again, adapt for your needs, but do try to avoid mixing more than 2 to 3 typefaces (in all applications).