There are practically 2~3 Fried Chicken shops every corner in Korea. At least 100 brands as Chain stores. Every one of them are good but avoid the cheap ones. They use bad oil to fry the Chicken. Cheap ones are under $10 per a whole chicken. The proper ones are $15 or above. The brands with reputations are "Kyochon", "BBQ", and recently "Oppadak" is recommended. 

Hi, George. 

I would like to recommend you a very unique place with a great history and which is not a franchise, located in Garosugil street of Seoul. 

It's called "HanChu" (Hanchu) and it was even awarded as The World's Tastiest Fast Feasts for Fried chicken in 2013 by Chowtzer Awards. 

There are so many fried chicken restaurant in Seoul and most of them are franchisees. So you would be better to choose franchise brand than to find the place. 

I give you a list 

1. BBQ Chicken(치킨)

2. Oppadak (오빠닭) Chicken

3. Kkanbu Chicken (깐부)

4. Kyochon (교촌) Chicken

5. Goobne Chicken (굽네) 

6. Nene Chicken (네네) 

7. DulDul (둘둘) 

If you want to visit one of them, please ensure that the restaurant has seats to eat. Many chicken franchisees in residence area may be for delivery only. Otherwise most chicken restaurants in downtown in Seoul has seats. 

Actually koreans are not fund of fried chicken because they are very health conciuos, what you could try is grilled chicken with chili sauce skewered between onion leeks. 

Its a street food and Its very delicious I had one around Insadong area. here is what it looks like

There are lots of places. I think the safest choice would be Kyochon chicken, Which also delivers nationwide as well. If you have a local friend, or staying at a hotel, simply ask them to order for you and you'll get it at the doorstep. You can pay with credit card or cash on the spot.

Check this out :) 

http://zenkimchi.com/restaurants/restaurant/8-best-korean-fried-chicken-joints/