I have to agree with Jack on two points. First,when I was running both services at the same time I felt that Qobuz had better SQ, not only on MQA vs native Hi Res files, but even when comparing Redbook versions. Not a huge difference. I could have easily lived with either one, but if you listened critically the differences were there.
I also agree that the only way to know for sure is to sign up for the free trial and compare them yourself. But.... this is much easier said than done. Both service do not do a good job at identifying the sources of each album. For example, they both have quite a few copies of the Miles Davis Kind of Blue album but give virtually no information of the source of each version. Just like with CDs or LP different mastering most often sound different. So it is very difficult to compare the two services. Since you have a hard time knowing if you are listening to the same version of a recording it is tough to know if any SQ differences come from the different masterings or the different services. I found the only way I could be reasonably sure I was listing to the same masterings was to pick something that was a brand new release and if it was only on the market for a week or to I could feel reasonable certain that there was at that point only one mastering floating around.
As to doing a shoot out at a G2G I would be careful about that. It is good to have another set of ears or two to get some different perspectives, but I would at least have the decision making session attended by only tow or three other people. The differences between the two services are not going to be bold, but rather exists around the "audiophile edges" and as such may be tough to discern if you have a large group of people in the room. Not only will a large group force people to listen off axis in sub-optimal listen positions, but putting a significantly larger than usual number of bodies in a room definitely changes the room acoustics and therefor the sound as compared to how it is when you usually listen to your system.
Having as shoot-out type event as a meeting topis is all well and good on it's own, but I would suggest that you do the meeting outside of the listening you do for decision making purposes.
Lastly, while there are slight differences in SQ between the two services I think the bigger and more significant difference is in their library contents. The two service seem to cater to different audiences. Tidal focuses more on Urban and more current artists than does Qobuz, which I found was better for Classical, Vintage Jazz and more Classic Rock type music. (no comment on either collection being better or worse that the other, just reporting what I saw in the catalogs) This should be no big surprise considering that Jay-Z was a long time principle in Tidal. So when comparing the two services take some time and look at the catalogs that each of them offer. IMO the SQ differences are relatively small and it would be more important to me to be able to get more of the music that I would tend to listen to. (My experience with Qobuz was mostly before their US launch, when I had a European account with them., so I can't really vouch for what the US catalog look like right now, but the idea is still the same.