I've used
this Swiss Gear pack on and off for a year or so. It seems to be well built, and is convenient for security (I won't get in to the debate about whether it's faster than puling out a sleeve). It's also very spacious. In fact, if I pack it fairly full, it's nearly as big as my 22" carry on. However I've never had trouble from a GA taking it as my personal item. The only catch is you have to be a Sam's Club member to get it for $39.88.
Chris