I love brutal crits where everything gets blown to pieces in the first 5 laps then you have 40 minutes to stare at your opponents in the final selection. A slight uphill sprint with a long finishing straight is nice for me too. And generally the tougher it is the more I enjoyed it.
You don't finish a good crit saying "That was fun-lets do it again!"
You finish a good crit gasping for air, dry retching, not knowing or caring where you came in the bunch sprint, simply glad that torture is over.