The Clarett and the UR824 are both in the category of "usable and great" to me, regarding the sound quality. I've never listened to them back to back though.
I'm using a Presonus Quantum now because I was interested in the low latency stuff. It's great for amp simulators for me, it's like playing through a real amp. Also for tracking through native plugins in general. Use your computer the same way as an Apollo, but with most of your native plugins instead of UAD ones. (other than plugins that introduce significant latency, like Pro L2, Elevate, as two examples)
The clarett has "acceptable" latency, but it's not at the top of the pile. Steinberg is also in the middle of the pack I think, probably a little slower than clarett. You're probably still going to have to use direct monitoring. The Audient gear is down in that range as well, regarding latency.
One I'd really like to investigate is the Tascam Celsonic US20x20, but I haven't had a chance to audition it yet. It's in the similar price range as the other ones here.
I'd probably pick the Clarett over the UR824. Next week I'll be getting a Clarett OctoPre for my main rig here, to go beside my Presonus stuff.