I can't really speak much on FFXV which I dropped pretty quickly. I may give it another try some day.
I definitely liked XVI. It leaves a bit of a weird taste, being extremely weak in some aspects and extremely strong in others. Interestingly, the weak parts are the rpg parts like questing, exploration and story, but the character action game style combat is really fun along with superb setpieces, visuals and music. They really tried to do something different and although it didn't come together, there's a lot to praise. I was genuinely bummed to hear it didn't perform sales wise as I do like the game, and the dlc which adds even more powers to play with in combat.
I adored remake. I'm not an FFVII guy, I started playing the series with FFVIII, so I didn't feel like they needed to leave midgar in part 1 or anything like that. Taking it for what it was unrelated to the original classic, I had a ton of fun with that game's world and characters except whenever it got all meta and pretentious. Rag-tag eco-terrorists vs evil megacorp for the fate of the planet is a great setup for a story, adding dumb shit like spectres and multiverses and Sepiroth smirking because he's in control even though you just killed him like 5 times really hurts the narrative. None of those story failings matter though because I'm having so much fun hanging out adventuring with the main party who are just amazing. Like when they're surrounded in the top of the shinra building at gunpoint and it's like "who even are you guys" and everyone strikes a pose and Barret goes "I'm Avalanche!" and Aeris says "I'm your local florist!" and Red's like "I'm a lab rat dog...thing!" they crack me up. Then there's the amazing battle system where all the characters have different, interesting playstyles. On hard mode, the variety of tactics needed to achieve pressured status on an enemy so you stagger them actually manage to combine the strategic depth of a turn based Jrpg with the fast pace of an action game successfully, making it a blast to play.
All that goes triple for Rebirth. The graphics suck compared to the PS5 version of remake but the trade off is bringing back the old school feeling of Jrpgs being enormous adventures you can get lost in with a ton to see and do. You can have an awesome card game battle against RedXIII while he's moonwalk dancing in a human disguise, or play an amazing piano minigame with Tifa in a bikini. You can fight insanely hard VR mission gauntlet challenges, there's so much game here to sink your teeth into. The serious, dramatic direction of the story still has my eyes rolling with how dumb it is... But the fun, adventuring side of the story is a laugh riot, whether its jammin' to salmon the doge's escort mission theme, Elena getting mad about vanilla ice cream, or Yuffie swooning at the sight of a muscle man's hairy pecs dancing. It was a huge downer to hear not many people even bought such a fun game. All I could do was buy more copies and gift them to friends! Hopefully lots of people are waiting for the trilogy to be completed before they buy, but if they try to play all 3 games at once they might feel a bit daunted when Rebirth alone is bigger than most games out there.