I've had a few different harnesses and currently use the fhf, and it's my favourite do far. I had an AGC cub, and felt it was a little too bulky and didn't like the lid. I switched to marsupial and really liked it, preferred the forward opening lid over the AGC's, and it was nice and low profile.
Recently picked up an FHF, partly because I like the way you can run bear spray on them the best, and partly because I just liked the look of em so figured I'd give them a shot. They're my new favourite. The backwards opening lid doesn't bother me at all like the AGC did, it moves out of the way better to put your binos back in, if that makes sense. With the marsupial, I liked that you could just leave the lid open if you were walking and glassing a lot, but it left the binos exposed, and opening and closing the lid isn't ideal if you're doing it all the time. While you can't leave the FHF open, I don't find the lid bothersome for access, and even if you don't bungee it shut all the time, it always provides a little bit of coverage for the binos. As well, the marsupial is open on the sides and can let debris in, and while the fhf is as well, it fits tight against the eye cups, keeping them cleaner.
Can't go wrong with any, but I'm liking the FHF best so far.