Hi Chev and all,
Two important criteria, rugged construction and gain. The first is paramount, the second is a bit iffy because little gane is to be had in an omnidirectional 11M CB antenna. A good compromise is the typical 5/8 wave, the brand is your choice. Never mind all the hype and opinions read here, the choice is yours and may common sense prevail.
Here's a good example of the CB mentality, beware half cocked rifles and misfired rounds.
"then when the federal govt saw that cbers were getting zapped by metal antennas, they changed the rules and required the antennas to be made of fiberglass."
Apply common sense to the above and like me have a good laugh. The only mandated requirement is a warning label on antennas, masts and accessories, I'm sure you have seen them. They're funny too, don't let the antenna fall across power lines, well, DUH.
Does anybody remember the opening sequence of the Mr. McGoo cartoons? Driving his car on the power lines and crashing into a pole transformer was a scream!
Edit;
Let me relate the experience of Jack WA2V with that Avanti Astro Plane antenna. After arranging a test with several knowlegable CBers in his area including me he carefully noted all signal reports using his Rad Shack 1/4 wave groundplane. We then mounted the Astro Plane in the same position on the same mast and repeated the test, absolutely no change but one noted later. Several neighbors complained he was wiping out TV reception on channels 2 and 5 being the worst. Back to the groundplane, the complaints ceased. Examination of the Astro Plane revealed the top elements to be resonant on the center frequencies of those channels thus amplifying the second and third harmonics of the 27MHz fundamental. He disassembled the TVI O Plane, returned it to the dealer, demanded and got a full refund but not until we threatening to bad mouth the antenna and the dealer on the air. One important fact I discovered is the Crap O Plane is constructed of the same materials as the average TV antenna and being larger and a nice windjammer, flimsy would be a good description. Draw your own conclusion whether or not to buy this thing.