Well, it depends on what you want.
I've played both, but way more FF 14 - although it should be said that I found it boring when I tried it the first time a year ago, but am having fun now after giving it a second chance.
PSO2 has absolutely much more engaging combat. Everything outside of it seems like a complicated clusterfuck though with a gajillion different currencies, progression systems, lootboxes, battle pass, etc. I'm looking forward to New Genesis though, since it has the opportunity to streamline everything.
FF 14's combat is whatever for me. It something that exists to have some variety, but so far the main meat of the game has just been doing quests to learn about the world and story. Well and the "casino" after I've unlocked it.
Perhaps paradoxically (but not really if you think about it), I'm finding FF 14 much more chill and "generous". Since it's a subscription-based game it doesn't need a dozen different systems designed to pull more money out of your wallet and stuff and feels "fair".
As such, the free trial of it feels basically like a fully-fledged paid 100 hour RPG that just happens to be playable for free instead of a designed F2P gameswith all of its usual trappings. That's more appealing to me (and the story focus). It's
much slower though especially at the beginning - I bailed after 10 hours the first time because it felt like all I did was mundane fetch quests with a combat system I don't really care for, but got hooked shortly afterwards. I assume the streamline patch will make that more bearable though.
...That turned a bit ramble-y, I hope I made my point(s)