You can use almost any red chile you like here. A ripe jalapeño, serrano, or Fresno would all be delicious, but I prefer dried chiles, particularly chile de árbol. You can also push the heat further than you would with a salsa de mesa because this salsa works more like a dressing. It coats the shrimp without penetrating it, so you get only a little with each bite. I used 14 chiles de árbol in mine! The salsa was very hot on its own, but much more palatable with the shrimp.
Chiltepín would also be great. For less heat, use guajillo, ancho chile powder, or hot paprika, alone or combined with a few chiles de árbol, red pepper flakes or cayenne.
