Based on my many years of DX'ing here in Texas, mainly around the Dallas/Fort Worth area, I'd have to include these:
550 KTSA San Antonio (directional at night but still covers a lot of real estate in South and Central Texas)
570 KLIF Dallas/Fort Worth (a nighttime pattern protecting WNAX Yankton SD limits their range but overall it remains quite an impressive signal)
620 KLKI Plano [Dallas/Fort Worth] (runs IBOC but still has decent skywave, although for many decades as KWFT Wichita Falls it had an absolutely killer signal)
930 WKY Oklahoma City (not what it once was, but still an impressive signal north and south over the Great Plains)
1270 KFLC Fort Worth/Dallas (good, although it was much better as the legendary KFJZ with their tower site across town in west Fort Worth)
1280 WODT New Orleans (the old WDSU; once had a dependable signal into much of Texas, now not so much)
1320 KXYZ Houston (solid coverage over much of South Texas)
1330 KNSS Wichita KS (formerly KFH, still rather impressive despite being directional NNW/SSE)
1350 WWWL New Orleans (the former WSMB, same story as 1280)
1430 KTBZ Tulsa OK (once the legendary Top 40 KELI, still has a signal that blankets much of Texas and in fact destroys co-channel KEES due south of them in Gladewater TX)
Honorable mentions go to WIBW 580 Topeka KS, WREC 600 Memphis, KARN 920 Little Rock, and two stations in Kansas City: KCSP 610 (the former WDAF) with its impressive non-directional signal and KMBZ 980, which is directional but doesn't really look that way.
