The fuck? We've had multiple threads based largely almost around people on here shitting on Five Guys, but people in here acting like its one of the best fast food burgers? Granted I like Five Guys (I'd take their burgers over a lot of other places, not just fast food), and defend them as far as being good, I just think they're massively overpriced. But what the hell?
In 'n Out is overrated I think, but if you like them its almost impossible to beat value.
I haven't had Whataburger in forever (since I was a kid and we went through Texas). I've thought about trying them but pretty meh since they have Coke (prefer Pepsi) and they don't look special enough to go out of my way to (although being open 24 hours working overnights I'm sure I will try them).
OP, have you had Culver's? They're based out Wisconsin but there's several down here in AZ and so I figured maybe the Southeast might be similar. I like their burgers. Its not spectacular but solid and they have the best cheese of just about any chain, I'd take them probably 2nd for fast food burgers here (Phoenix metro area) behind Five Guys.
I personally like Carl Jrs, but they seem hit or miss, and have been more miss down here so I never eat there. Which they're kinda like Whataburger (you mentioning their drink sizes for instance, Carl Jr is same way, plus they at least have Cherry Coke in their fountain).
If you're in the NM region (they were slowly branching out into AZ and TX), try Blake's Lottaburger. I wish they'd get one here already. They have Five Guys quality burgers for more reasonable prices and they had Cherry Pepsi in their fountains (Culver's does too, but its not cold and their ice is practically already melting out of the machine). Have some other unique little aspects that I can't recall (they have some season fries or something?).
We've eaten Fatburger (think they're mostly in CA?) a couple of times. There's a couple in casinos down here. Unfortunately have to go into the casino (smoke smell...and weird people). I really liked them the first time. 2nd time not as much, but still decent. They had switched from Pepsi to Coke (but I think that's due to the casino as their free fountains had also changed that way), but even the burgers weren't quite as good but might have been time (although the first time it was like 1AM on a weekday so you wouldn't think optimal but it was good).
Not sure if they're still doing it, but if there's a Cheddar's nearby they were offering a 4 burgers and fries for $20 deal. And they have pretty good sized burgers. I used to like them but their burgers now have like a sweetness to them (reminds me of Cheesecake Factory) that I don't like, but others might.
And underrated burger would have been Chili's, but then the last time we ordered from there they sent a roadkill (i.e. those slapped together, where they don't even form a patty and there's like bits of gristle holding big chunks of the meat together - I have no clue why places do that, Applebee's started doing it and I think Freddy's Frozen Custard does it too, and I hate it). But have had good experiences other times eating there, including one time, I think we were finished eating and paid as quickly as if we'd gone to Five Guys as they had our order and food out to us (and made well) within like 15 minutes and while they weren't crowded busy they weren't mostly empty either.
I used to like Famous Dave's but they play country music now and I've had maybe one really good burger (I usually get the Devil's Spit) out like the last 5 times I've eaten there, so they're another that I kinda gave up on. Red Robin is overrated and their bottomless fries are a joke (most of the time its plain steak fries, although sometimes they season them?). The last 3 times we ate there (was always with family), had to constantly ask for more fries because they'd bring them out in small little baskets with like barely 5-6 steak fries like they were cheaping out on fries or something.
Fuddruckers was ok. I don't remember how their food tastes, I don't recall it being bad but I don't recall it being good to the point I actively think of them. They have a variety of options (think they have buffalo and maybe ostrich burgers too?)