If you were to look at my roster of characters in the Character Builder, you'd notice a preponderance of the following:
- Star pact warlocks, and infernal pact warlocks and hexblades
- Tome-wielding summoner wizards
- Shielding swordmages
- Swarm druids
They're mostly arcane, and they all have some pretty flashy class features. But what really draws me to these options is that they rely on Constitution as the primary or secondary ability score. Why should such a design choice appeal to me to the exclusion of others? Obviously, a high Constitution score offers better hit points, more healing surges, and a good Fortitude score, but I think my preference has more to it than liking survivability and well-rounded defenses.
For most of the life of Dungeons & Dragons, Constitution has been a passive ability. In AD&D it determined a character's chance to survive specific events: resurrection and "system shock." In 3rd edition, Constitution powered the Fortitude saving throw, which saw more frequent use. But Constitution was the primary ability for exactly one skill: Concentration. Even in 4th edition, Constitution still has only one skill tied to it: Endurance. Allowing for edition differences, I'd still argue that checks for both those skills are made in reaction to events more often than they are to cause events.
For those classes I like, though, Constitution plays a more active part. It drives their melee and ranged attack powers, or determines how far they can push an opponent, or how much they can help an ally. My characters will still need Wisdom and Intelligence checks for exploration, Charisma for interaction, and Strength and Dexterity for getting around. But by making Constitution an important part of my character's combat experience, I feel more like I'm using 100% of my character sheet.
Knowing why I like what I like is important because that knowledge can guide my choices in other games, or (more topically) other editions of the same game. Infernal pact warlocks might not always be available, but if I can build another character that gives me the same feeling of firing on all six cylinders, chances are I will have the same amount of fun.