A great logo quivers on the page. Its component parts at once complement and contrast, creating a slight tension that makes the whole look as though it is about to leap right off the screen.
The key to achieving this effect is good composition, and as with all things that appeal to our senses, this comes down to balance. Consider a cocktail. If the base is sweet, you’d want to add something bitter or sour to play against it, lest it become cloying.
Logos should balance visual elements in much the same way. Apposing curves and angles, verticals and horizontals in the right proportion is a strategy to look out for, and the following two examples absolutely nail it.
This logo design for CorkCount.com, by danielwatson, places a design with prominent circles — the magnifying glass, the half-moon glare, the cylindrical cork and its hollows – against a vertical line and tall, narrow typeface. Beneath it, for the slogan, the designer chooses a more curved cursive, softening the contrast and bringing the logo together into a state of satisfying balance.
This logo for Smitten For Good, by chocolate992, employs a very similar balancing mechanism: curvy critter on the left, severe, tall and narrow sans-serif typeface on the right, and a circled word in between to mitigate the contrast. The contest holder didn’t have to make this compositional request explicit. His excellent selection of example logos, which include the designs for Locaray, Roosterori and Whalero, make his desires absolutely clear.