TLDR: I use Cloudbounce when I'm on a budget because I get unlimited mastering for $21.90 per month and I'm very happy with the quality of the masters, and I use Discmakers when I have the extra budget and/or I know that I'm going to push the song to playlist curators and possibly run ads for it.
I have used both Cloudbounce and Discmakers Soundlab to master my music. Ideally, I finish recording my albums in a professional studio, to let an engineer record my vocals, and mix and master the tracks. However, I don't always have the budget to do this, and after moving to a new state in 2019, and having COVID disrupt everything, I have not found a new studio in which to finish my albums. So I record my music and vocals at home, using a Behringer UM22 Soundcard, which I plan on upgrading to a Scarlett Focusrite 2i2 when I get the extra $200 to do so, as I've heard music recorded on it, and it is has less noise than my Behringer soundcard.
For my most recent album, "Gummy," I ran a Kickstarter campaign to raise money for the album release, and let that dictate my budget for the album. The more money I raised, the more songs from the album I could spend extra on mastering for. I had 4 or 5 songs that I really wanted to send to Discmakers because they were the standout tracks for me. I ultimately ended up with the budget to master 3 tracks that way. At $59 per track, plus tax, it came out to about $190 for those 3 tracks. I mastered the rest of the album using Cloudbounce, which right now costs $21.90 per month for unlimited mastering. If I had mastered the entire album that way, it would have cost $2.19 per song to master, so it's then a question of value vs budget. eMastered is also an AI based mastering service, but I have not used it, and at $39 per month, when you pay monthly, I probably won't try it, as I'm already very happy with Cloudbounce at $21.90 per month.
To me, Cloudbounce provides the better value when budget is an issue. When I have the extra budget, I will definitely choose Discmakers Soundlab as an experienced human engineer will still be able to improve the master upon listening multiple times. There's also a time difference between the two services.
Cloudbounce takes just a few minutes to master a track, and has a bunch of different genre options to choose from, so you can try out multiple versions and decide what you like best. You just upload your finished song with 3-6 DBs of headspace, and let the program do the work.
With Discmakers, you fill out a quote, with a very detailed form, as well as the finished song with 3-6 decibels of headspace, and then a human takes the time to master the song in their studio. Usually the turnaround time is 3-4 days. They then upload the mastered track to the website, where you can download it.
In the video above, I break down the process even more, showing the steps in both Cloudbounce and Discmakers, and I include the audio from the Cloudbounce versions and the Discmakers versions, for all 3 songs, so you can hear the difference.
If I know I'm going to pitch a song to playlist curators, and possibly run ads for the song on Snapchat as well, I will definitely make sure to pay the extra to have Discmakers master the track. The difference in price also isn't as drastic when you compare mastering one track on Cloudbounce (which you can either do with the unlimited mastering for a month at $21.90 or for an individual track for $10.90) versus $49 right now for Discmakers to master the song. My most recent single was mastered by Discmakers, and I think the extra cost resulted in a better performance on Spotify. Even if it didn't, I'm happier with the higher quality audio.
Whichever mastering service you use, I wish you good luck and success!