When it comes to content, do whatever will please your human visitors. The one thing Google does NOT want is any content that was created solely to "please" the search engines, without any regard for its impact on human visitors. What Google DOES want to see is content that's interesting, useful and engaging for people.
As it happens, that's the same sort of thing sought by people who are in a position to give out valuable links.
The links that matter -- links that Google will most likely count in your favor -- will come from other site owners who find your pages, like what they see, and decide to link to you because they think your site is a good resource. If you make your site attractive, easy to use and valuable, you'll be more likely to get those kinds of links.
If you think your customers (and these other site owners) will be more likely to visit and approve of your site if it has promotional language in the page titles, then use whatever promotional language you think is appropriate. If your audience might be "turned off" by too much of a hard sell, use less promotional language, and consider placing it in a less prominent position on the page.
There are no "rules" for what content you should or should not have or where to place different items. It all depends on your target audience. Think about what they expect to see. Consider what will get the best response from them.
(And just to make sure this is clear: the links are not simply going to appear by magic. You'll still have to put some effort in to getting the word out about your site, to help those other site owners find you.)
When it comes to the snippet, of course, Google will decide what to show. Regardless of what content you have on your page or what you put in the page description META, Google will display whatever text they think is most relevant for the particular search query. It may or may not be what you "chose," but frankly Google doesn't care what we site owners "choose" in that regard.