Not had Whataburger. But I'm a burger guy and have had several on the list in the OP. But...
I just had one of the best burgers of my life today. Place called Lunchbox Laboratory. Bit expensive at about $14 a pop with side of fries. Totally worth it. This place has "Dork," duck and pork patty. Also has "Churken," chicken and turkey. I had their homage to Dick's Deluxe, a classic Seattle drive-in menu offering. They leave it done medium and the juice and grease runs on the plate and you need 6 napkins to clean up. Friends who had been there a lot said they use "American' Kobe beef raised here? Don't know if that is possible to keep the price to $14 but damn worth the trip to one if you're in the Seattle area.
Fish's best burger list:
Lunchbox Laboratory; Bellevue, WA
Lottie Moon's Bar; Oxford, OH
Honorable mentions:
Fuddrucker's (chain)
The Counter (chain)
And Five Guys, because they know bacon on a burger should be crispy... you know, for texture. Just seems right to me.
Not really a fan of drive-thru fast food but if I gotta do it, Wendy's.