red for sure ,much better in flavor and heat!
Fresh red poblanos aren't available here unfortunately, only dried.
Here's another simple answer.
Poblano
The name Poblano is derived from the name of a valley called Puebla that is located south of Mexico City where these chiles were first cultivated.
Other Names: Poblano refers to the green, or less mature, stage of several different varieties of chiles including Ancho and Mulato.
Uses: This is one of the most popular fresh chiles used in Mexico. Always use cooked or roasted, roasting enhances the full and earthy flavor. The large size and thickness of flesh of the Poblano makes them ideal for chiles rellenos or other stuffed chile dishes.
Ancho
The name Ancho means broad, referring to the broad and heart shape of these pods once they have dried. Anchos are probably the most commonly used dried chile in Mexico where many varieties are cultivated. Anchos are so popular they may be found under cultivation somewhere in Mexico year-round to supply market demand, but will also grow well in the right regions of the U.S.
Other Names: Ancho is the red, ripe form of the green Poblano chile. Not to be confused with the Mulato, both chiles are called Poblano in their green chile stage, Ancho ripens to a deep red and Mulato a dark chocolate brown color.
Uses: This is an excellent all purpose dried chile and chile powder. The medium spice combined with the sweet dried and concentrated flesh is perfect for most recipes including sauces, moles. When in season, try roasting a perfectly ripened Ancho and indulge in a superb fresh chile.
Mulato
Mulato means and is a light brown cultivar of a ripe Poblano, comparable to the ripe, red Ancho.
Other Names: This chile ripens from a green Poblano to a chocolate brown chile. This chile may be found mislabeled as a Pasilla in the U.S.
Uses: This is an excellent dried chile and chile powder. The medium spice and sweet brown flesh pair perfectly both fresh and dried. Try feasting on a fresh roasted Mulato chile when in season or snack on a few dried pieces as you formulate the perfect recipe for such a flavorful chile. Mulatos are a great choice for sauces and moles.
So an Ancho is a type of Poblano that ripens to red and a Mulato is a type of Poblano that ripens to brown. Of coursr either can be dried and most ripened forms of Pobalnos are dried, but drying is not a prerequisite to being labeled Ancho or Mulato; it just refers to their color when ripe and I see the names used with the chilies wheather they are dried or not. In the end it doesn't matter what they are called; by any other name they would still taste great.
I know that in the US produce travels an average of 1500 miles to reach the shelves of the supermarket. I also know that generally, tomatoes sold in US grocery stores are picked green for a couple of reasons. One, they are sturdier when they are green. Two, because they have to travel so far to reach the consumer, if they were picked ripe, they would rot before they reached their destination. Three, tomatoes are gassed before they reach the stores to induced them into ripening to red.I'd suspect the reasons you see a lot of green chiles in the stores generally fall along the same lines of why tomatoes are picked when they are green. I've also noticed at my local supermarkets that all of the ripe habaneros (yellow, orange, red) have mold growing on them. That is part of the reason I want to grow my own.
Whoever said green chilies are considered vegetables is a nut. Chilies are fruits, no matter the color.