I know I'm late to respond to this, but in case others are looking for something like this, I really like the Waterfield Air Duffel Carry-On as my underseat personal item. It's not the biggest, but you can cram it full, and it's one of the only items I could find which fit some off the more restrictive airline requirements for under-seat. I like the organization and it's well-built, but admittedly it's expensive.