I like the ones where the armrests will flip out of the way, too. I have 2: both are Scott. On my Trek 5200 I have the Scott bars with the piece in between the two sides to join it together at the top. On my Calfee Tri Bike, I have the same Scott bar, but without the piece that joins the two sides together. I'm liking that one better. The good part about the Scott bar is that the arm rests can be flipped up if you don't need them...or flipped down ready to use (or tied down if it is really windy). The Profile bars with the flip up pads are spring loaded, so they can be a little trickier to get into -- not bad once you are used to it. Also, for the Scott bars, there is room underneath the arm rests where you can grab your bars even without flipping up the arm rests. My husband and other triathletes that I know use the regular Profile bars or the Syntace bars. I haven't shopped for aerobars lately, but Scott is my bar of choice. When I got mine, they came in different sizes, so you could fit them perfectly to your needs. They also are adjustable for width and forward/back placement for the arm rests.
I've heard complaints about other "adjustable" aerobars being loose or rattling.