Me; I have teardrop on the early style clones, and round on the late A2-M4 clones--but NOT THE PIISANT CURRENT ROUND style. It's too small and I can't get a good thumb push on it (I'm left handed and reach around the grip w/my thumb to hit the FA). A lot of folks don't realize there are two different sized round ones, and the early large size is much easier to use.
Colt went to a round style FA for just one reason; it was cheaper to make. The first round FAs were .75 inches in diameter. Then, when the reinforced lower A2 type lower was introduced, they found that .75 inches fouled the new lower when used, so they startrd milling a flat onto the inside---which raised the production cost back up to what it had been w/the teardrop. That's when they dropped the diameter to .6 inches. My own pieces have the ealy diameter with the flat on the side. They work well, and are as easy to find as the old teardrop.
There, did I get the thread back to the original topic, and off the insult contest[:D]