The word "variety" comes to mine. First, a variety of terrains. I have driven across Texas on both I-10 and I-20 and have done sightseeing in the Big Bend region (scrub desert), Dallas & Ft. Worth (transition), and Houston (green and fertile).
But then, you also have variety of culture. I've been in a couple of the border towns and in the urban sprawl that is the "Big D" - and I've even visited Austin once. In San Antonio you get the history of the Spanish mission churches. In Midlands / Odessa, you get the modern oil-field towns. In Houston and Galveston, you get a coastal fishing and oil culture. In Ft. Stockton, you get an artist and artisan culture.
Texas is too big to be described in one word other than "variety."
P.S. I'm from Louisiana and still live near New Orleans. I'm not a Texan.