Some Virtues of Guinea Pigs

Squeakiness.
Just the right size to sit in your lap.
Big, beautiful eyes. Their eyes take up most of their head. If they were in a Japanese anime, they would look exactly the same as in real life.
Intense obsession with food - squeaks of anticipation when they're about to be fed, rummaging around the play area searching for it, eating it, checking neighbor's mouth to see if neighbor is eating anything, etc.
Willingness to stand on hind legs, leap through hoops, etc. in order to get food.
Cleaning frenzies.
Nice, kind of musky smell.
When placed on the chest of a reclining human, tendency to move up to snuggle under the human's chin.
Popcorns (an explosive leap in the air that guinea pigs do sometimes).
Freaking out about completely random things, like someone sneezing.
Getting really excited about sounds like the vegetable drawer opening, or a plastic bag rustling.
"Driving" around in their cardboard box.
Cilantro tug-of-wars.
Turning the play area into a racetrack and scurrying laps around the table legs.