Burger lunch today in Columbia, SC
I agree with the other poster. In addition I will recommend you consider Zesto's (several locations), Rush's (several locations) and the Salty Nut (on green st. near 5 points).
I'm one of the ones that likes Rockaway's. They've had an up and down period especially after the last building burned down. I feel they are in an UP period now and I really like their burgers. The Rockaway burger with pimento cheese is my fav.
I can't speak to the quality of Edna's burgers, but the hot dogs are good.
I'd suggest Hunter Gatherer, at the corner of Main and College. They have a good burger and if you ask they will cook it to your desired degree of doneness. Plus, they brew their own beer so you can have a nice leisurely lunch. No fries, though, last time I checked.
I've eaten my favorite burger in Columbia at the Cock n' Bull (on Rosewood Drive), but I cannot recommend that place because I have no idea if it is open for lunch, or even if the burger is always on the menu. You might try calling them.
I'm sure someone will recommend Rockaway's, in an unmarked brick building on Rosewood, near the intersection with Woodrow St, for their Pimiento Burger. It is not bad, but I am not a huge fan. Others are, so YMMV.
Finally, there is Five Guys, a chain restaurant that got its start in Virginia. While more of a fast-food burger, it is an exemplary and delicious specimen of that kind. Plus, their fries are great.
I have not been to Edna's #1, which is sometimes recommended here, so I cannot comment on it.