I have a Billingham Hadley Pro for my X-T1 and love it (bought it used on eBay). It was handy as carry on for my recent trip to Canada, holding the following:
* X-T1 with 35mm F2
* 16mm
* iPad Mini
* Passports and papers
* A few filters/adapters
While in Canada, it was handy as I was able to remove the liner that was holding the camera equipment and use the bag to carry my stuff for the gym (shorts, travel towel, Vibrams, shirt, socks, undies, and toiletries).