To be honest I didn't really find either of them overly compelling in TW3 (Relationship wise).
I think the choice ended up causing the entire triangle to be watered down, and that really hits me hard because I was someone who pre-release was in threads advocating for the choice, and saying CDPR would be mental if they didn't let us choose. Hindsight is 20/20.
In The Witcher 1 there was at least some extra depth to that triangle due to Alvin, and the choice you made with him and how that affected your relationships. In The Witcher 2 it was more focused, the clear 'in-the-moment' relationship lies with Triss, but there's the looming shadow of Yennefer and the myriad of questions that came forth from the current status of those characters, and Geralt (Amnesia etc). Not to mention the more subtle elements of Triss' character in TW2, like emotional manipulation, the Lodge's influence, the possibility of magical control and/or the Rose of Remembrance etc.
In The Witcher 3 it's literally just a choice. There's no greater depth to it other than, "Who do I want Geralt to be with?" And that's boring. Who you choose has no physical and/or emotional effect on Ciri, nor Geralt, or any important characters for that matter. You could argue Yen/Triss might have been left a little jilted, but there's not really any pay-off for that, no follow-up, each character just acts like the matter is resolved, it's cool and it's never bothered with again for the rest of the game. Ultimately it didn't feel like there was anything at stake, there's no conflict (Or compelling conflict), it just comes down to arbitrary personal preference (And I'll dare to say it, gave me strong BioWare vibes).
I'll probably end up with Yen on my next playthrough, just to make sure I've seen both sides of the romance, but I highly doubt that'll improve my experience at all (Actually it'll probably happen when the cringeworthy new dialogue is in, and that'll just make me hate it all even more), and to be honest if I play the game again after that, I'll probably just pick no romance, because as I said, it feels extremely arbitrary and pointless.