There is no "one". Your children are going to have to come up with enough money to buy at least ten different CDs.
I like "Pure Country" because of Heartland.
I'd recommend the "Strait Out of the Box" set, but if you must choose one CD, get his first greatest hits album.
I prefer the upbeat musical stylings of Freddie Gage.
For the Last Time, Live at the Astrodome is very good. Most live albums aren't that good but this one is great. Whatever you do don't buy the one he just released. I listened to it once and put it away. His worst effort ever in my humble opinion.
Go to Amazon and search for George and sample his albums. I buy a lot of my music that way. It helps me decide if I like a CD or not.
50 number ones...
http://www.amazon.com/gp/product/B0000CE752/qid=1137044987/sr=8-1/ref=pd_bbs_1/104-6152804-4383109?n=507846&s=music&v=glance
So, what'd you get?
I'm not really a country music fan but always loved the song "All My Ex's Live in Texas" so bought "The Best of George Strait", 20th Century Masters, The Millennium Collection. Its a great album.