Thinking of upgrading my Mytek Liberty DAC to?

Depends upon how much you are getting out of the system.
Qutest would be worth the effort to demo.
Likely more processing power.
Mytek DACs sound quite good.
Though I can't comment on Glass FX sound.

My suggestion: Element X MQA Streamer+DAC (competes with Mytek Brooklyn Bridge).
https://www.matrix-digi.com/en/products/321.html
Review:
https://www.audiosciencereview.com/forum/index.php?threads/review-and-measurements-of-matrix-audio-element-x-dac-streamer-amp.7782/

Hmmm...no other opinions?

What difference do you want to hear?  You're probably not getting a lot of responses because few people are likely to have listened to all of those DACs.  I haven't heard any of them.  If you can describe what you don't like about the Liberty or what you think is missing with it, you may get some recommendations.