I've had and carried both, and the ULA packs (Catalyst, Circuit, Ohm) blow the Exos line out of the water - IMHO!
The Exos is a decent UL pack from a major manufacturer. They've done some innovative things to bring the weight down, yet still have many of the extras that mainline backpackers like - lotsa pockets, cool graphics, and the nifty trekking pole carrier!
My biggest problem with the Exos was the shoulder straps and hip belt - they are stretchy! As you walk along, you can feel the pack bouncing. I had to repeatedly tighten the hipbelt as it kept stretching and sliding south.
Then there is the fiddliness of those tiny compression straps! They seemed to jam on my constantly, or refuse to release without significant care for preciseness in direction pulled.
Finally (and I hoped they've solved this by now), the mesh back on two of my Exos packs frayed or tore at or near the point where it stretched across the frame. Speaking of which, you should realize that the Exos pack bag sits well back from your won back - this allows significant air movement on your back, but also leverages the weight away from you - my back didn't like this.
The ULA packs, on the other hand, carry like a dream. I tried the Catalyst, Circuit and Ohm 2, and kept the Catalyst and Ohm - nothing wrong with the Circuit, just the other two covered all the bases. The Catalyst carries heavier loads when needed; the Ohm does lighter loads.
All three do an excellent job of transferring weight to the hips - the shoulder straps and load lifter basically keep the pack from falling backwards - my back smiles! (You can put the weight on your shoulders if you desire, but I don't!) I find it easy to reach water bottles in the side pockets while hiking. One strap on each side and the criss-crossed bungie on the front pocket handle compression easily, no jamming. The materials they use are sturdy, the workmanship excellent, and there is no wear issues with either my Ohm or Catalyst.
Finally, if there's something you'd like done a little differently on the pack you get, you can call ULA, talk to them, and they will likely find a way to do it - I found them very friendly to deal with on the phone (emails are not quite as good).
In short, I really like my ULA packs.
I have no connection to ULA, and paid for my packs with my own hard-earned money.