[dmforcier]

Nice big fat ones are good.

Honestly, peppers are rarely separated into sub-varieties, with the notable exceptions of bells, Japs, and Scotch Bonnets. For supermarket peppers like Poblanos, most casual growers just save seeds from the fresh ones they get at the market.

Or if you're not into starting from seed, Bonnie Plants usually has good ones available at your local big box stores. (But up north you might do better starting well before the plants are available at garden centers.)

You'll love your Poblanos so grow more plants than you think you'll use. Also be sure to try a Chiles Rellenos recipe. (I like stuffed with cheese and shrimp.)