At present I'm using Maui Jim hingeless titanium arms/frames. A few reasons why:
* The arms are flexible, flat and very slender, thus there is next to no noise able to penetrate the gel earseal where the arms of the sunnies sit against yer scone.
* Again because they have very flat and flexible arms, you don't get that annoying "my head's been in a vice" feeling after wearing them with your headset for a number of hours on end.
* The lenses fit the shape of my head well and there are no large open areas for stray light to enter my eyes.
* They are exceedingly light. You can be wearing them for hours and forget that you are wearing them. This is a double edged sword - see below.
* I have had no issues with heated/treated windscreens.
They do however, have a couple of drawbacks:
* When you look at some GPS's directly, they can occaisionally appear black/blank. Tilt/move your head ever so slightly - problem gone. I believe that this is more to do with there being a band of polarised material in the lens (which is quite easy to see when looking at the lenses from the front, they appear to have a horizontal band running across them).
* They can be blown off your head by a sudden gust of wind if you have them pushed up on top of said scone while not using them.
I have recently had my Maui's in getting a warranty repair for a cracked lens (they are covered by a very generous warranty - they were actually replaced FOC despite being over 12 months old), and had reverted temporarily back to an old pair of glass lensed Ray Bans that I used to wear before the Mauis. Talk about heavy sunnies!
Sunnies are like shoes in many ways. Each person needs different sizes/shapes etc etc. Choose what is best for you by begging/borrowing/stealing other peoples and "test driving" them in flight. You'll soon work out what works for you.