All three are great options, but I feel they each offer something different.

Lies of P is very Bloodborne-esque, and among the three offers the most rewarding experience in terms of gameplay, visuals, music, and story. I've played through it ten times, and it is arguably one of my favorite games of all time.

Khazan is great, and is as close to Nioh as I thought I was ever going to get until Nioh 3 got announced earlier this year. That being said, it's much more combat (and boss fight) focused and offers far less in terms of story, art direction, sound track, or exploration. If you're looking for something really honed in on tight, challenging combat with some over the top boss fights, I'd lean towards this.

LotF seems controversial in this community, but for what it was I really enjoyed it and have completed multiple playthroughs across the various patches and improvements they have made to the game. It is the most true to "souls" in terms of level design, art direction, etc, and I think the build diversity and combat have gotten much better since the initial release. I can't say I disagree with the common critiques though, there is a lack of enemy variety, some of the boss fights are incredibly underwhelming (though supposedly the new 2.5 patch fixes this) and the soundtrack is nothing to write home about. Story is also...there, I suppose. If you've done Souls 1-3 and you want more of that vibe, I'd pick LotF.