One of the most efficient and powerful build in the entire game and also good for Amrita farming and overall viability is the critical Living Weapon build especially with Kusa Blade spin.
There are two armor sets that come up on top when people are making this build. The first is the Fanatic set. To craft them you need to farm that Omni Bozo which is a real pain in the ass. On top of that you need to invest a shitload into stamina just to wear it. And you have to invest 7 in body and strength I believe. If you get it off revenants it's even worse you have to invest 14 in each. But that is the armor set most people are going with but it's not by choice.
The other armor set is the better option. It's called the Crimson Sanada set. Not only is it a better set bonus it doesn't require any of that stamina upgrade or other upgrade cost to wear so you can spend them on your main stats. Imo best armor set for the build. The downside : you can't get it in the game. It was only given as a code for people who preordered the game. When I realized this I was saddened. Because I'm into min maxing my character having the second best option didn't sit well for me lol. So this is a PSA to everyone who's in the same boat with me. I found out that you can just buy the Sanada set on EBay. People are selling the code for only like 4$. lol I brought mines last night. It's so weird buying one of the best builds in a game for 4$, who would have thought that a pre order bonus would trump almost everything in a game. It's an interesting and fascinating concept and I found it a bit ironic and humorous lol. Usually pre order bonuses are like just a portrait or skin, maybe a trash weapon, first time in playing a game where it beats out other endgame content! Lol Just wanted to share with you all.