I subscribe to both, since my streamer fully decodes MQA. But to be totally honest, I can't say I can tell a consistent difference between the highest resolution content of the two services, at least on my system (Node 2i, PS Audio Stellar Gain Cell, PS Audio M700 monoblocks, Magnepan .7s and Hsu sub). And on those few things on which I think I hear a difference, it's supremely subtle, and not the kind of thing that would make me say one is better or worse than the other.
For now I'm keeping both, since their catalogs are somewhat complementary, with more classical content on Qobuz and more popular content on Tidal (at least among those artists I have an interest in). If something happened and I had to lose one, I'd probably dump Tidal and keep Qobuz, only because I find myself exploring unknown classical more often than I explore unknown rock/pop/jazz/folk.