Yea, for barbs, all popular builds are based on your set first, skills are secondary and can be all over the place.
Raekor's Furious Charge build seems to be the most powerful right now, and requires Raekor's set (And usually Vile wards, which VASTLY increase the damage). Usually used with this is a second small set, Strongarm bracers for extra damage (charge will cause knockback). TONS of cooldown reduction is best. Leoric's Crown is great (Even though I cannot find the damn thing)
There are a few newish builds out there that go back to using Whirlwind as a primary attack, they will likely have just as strict gear requirements. These builds often rely on procs that are not proc-coefficient based, such as the poison and physical bleed damage legendary gems. These also rely on having some great 1h-ers like Odyn Son and Thunderfury.
As far as high-end builds go, most all use Pride of Cassius belt for longer Ignore Pain regardless of other details.
Another option you can go for is leap kings. I'm personally not a fan of the Raekor set so I chose might of the earth + immortal kings. As far as passives play around and find what u like. I personally like shit tons of survivability so I chise lots of defensive passives. As far as jewelery a rorg is a must with a socket, the other ring what ever is good with a socket. Neck, if you can get lucky and get a good hellfire wear that, followed by in my opinion the Lightning immunity followed by arcane immunity necks, followed by what ever the best thing u got is. Your neck and rings should all have sockets. As far as gems the bleed and poison gems followed with what ever u like. I personally needed the CDR gem so I choose that. Here is a link to my barb so you can see what gear is needed and what not, have fun!
I run one of those newer WW builds. I like it because it can work with just about any gear you have, unlike Furious Charge or Leap Quake. Yes it is better with high end gear, but the gear doesnt make the build work, it just makes the build better. Leap Quake is very hard to use if you dont have MoE set along with Lut Socks. FC build doesnt work well if you dont have Raekors and a great 2 handed weapon.
I run 3 pcs of Raekors along with 3 pcs of IK with a RRoG, so I get perma-ancients. I run Odyn Son and Fulminator, but was running Devil Tongue before I found my first Odyn Son. This build wont be clearing super high grifts anytime soon like a good FC build, but it can be tons of fun. With 0 high end gear, you can go into T1, maybe T2. With better gear, that goes up to T3/T4. With great gear, I am clearing T6 with little difficulty and my solo grift record right now is gr27 (which isnt crazy high or anything, but for me I feel like I accomplished something) I could go much higher if I had a double unity ring.