Best Ceviche in town?
Zocalo and Nacional 27 are pretty good as well. Zocalo's are more traditional. Nacional 27 has creative ones. Since chef Randy left to open Province, i hope the quality of the food hasn't suffered. For an offbeat choice, try the ceviche at Irazu. The Tikoys (Costa Ricans) eat it with ketchup and saltine crackers.
I really enjoy the ceviche at Rick Bayless's Topolobampo. The tasting of each of the daily selection is the way to go. Nice amount of heat, plus the nice freshness of the citric juices paired with the fruits.
Carnivale also has a good selection - the Kona Kompachi and Tuna Tiradito are must.