RH 660s. I was skeptical at first, but it has really held up. I get really good signal reports and people always say they're surprised when I'm using a UV5R. I did drill the microphone port open a little wider by the way and I think that helped get some more gain/clarity as well.
Note that the RH 660s is 27 centimeters collapsed (11 inches), and 1 meter fully extended. It is rigid so not one of the floppy antennas. Collapsed it can take abuse, but when extended, bending is a risk.