I have a F Stop Tilopa, Mindshift r180 and Mindshift panorama.
The f stop Tilopa is the best built, but the Mindshifts are not far behind. Mindshift r180 is probably most comfortable, mainly due to shoulder straps.
Tilopa is my hauler. It fits everything and asks for more. The reason I went with the Tilopa over the Loka is that you can use the straps to make the Tilopa about the same size as the Loka, but you can't expand the Loka. The Tilopa, with a pro insert, can fit in the overhead of a CRJ 200 as long as you have it strapped down to the depth of the insert. As long as you are ok with carrying your camera outside your bag, this bag with a capture clip is a great combo.
Mindshift r180 is my bag I use to get everything to a site that the cameras will be out of the bag at all times (like a football game). It hauls a lot (gripped 5d3, 1d4, 120-300 w/1.4x extender attached, 70-200 2.8, 580 exii, 24-105 f4, monopod, plus accessories), but not as much as the F-stop. What is great about this is that once I get to the site, I can take the beltpack out of the bag and use it to carry accessories/lenses while I carry the cameras.
Mindshift panorama - awesome everyday camera backpack, will become my go to. Went to disney and Biltmore recently and this was perfect. Great access to my camera and hauls enough for a day trip. I had a 5d3 ungripped with 24-105 attached, 580exii,
and a few accessories in the beltpack and a good amount of space left in the upper portion. What I liked about this bag is that it is easy access to your camera very quickly, but keeps the camera in the bag so you don't have to have straps or worry about banging it on something. Also, the ease of taking it off and on while at Disney to ride was great. With the Fstop, I would have carried my camera around on a capture clip to get quick access to it (the people I travel with are great at waiting for me to take a picture, but by the end of the day getting the camera out and putting it back in everytime you want to take a picture is annoying and slow) and then every time i wanted to take it off, I would have to take the camera off first and get someone to hold it or set it down and then fool with the backpack.