I have SA, Synapse, and Brain Bag (yikes I have a problem) and I think Synapse might be my favorite but I can't see using it for commuting back and forth to work with a laptop. Maybe I prefer the Synapse because I use it for vacation. The BB is so huge it really makes me not want to use it because it will be much too heavy if full. But if you need that much space then you need that much space. I do love the look of the SA the most. It just seems sleek to me. I had good luck with mine going to/from work when using a TB Brain Cell.
I never tried it but you might have good luck with the SA as a carry on. It can hold a lot and if you pack clothes it won't be very heavy. Plus you can probably still fit it under the seat of a large plane. I've crammed my BB under there before.