From a quick look over tier and the possible off piece, it comes down to Garrosh shoulders vs. Tier Shoulders. Helm, Chest and Gloves are Haste/Crit and Legs are haste/mastery with 2x Yellow while non-tier is crit/mastery with 2x Blue.
However, all this depends on what our stat weights will be when 5.4 hits. RPPM nerf is in effect in PTR currently, that will affect the value of Haste greatly. I believe we will be back to Crit > Haste > Mastery for SV while BM could still be Haste > Crit > Mastery.
Also BiS weapon will be from Paragons of Klaxxi, Haste/Crit with red socket, can't get better than that!
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Quick BiS at first glance(No trinkets, need to wait for numbers):
Head:
Headguard of the Unblinking Vigil
Neck:
Gleaming Eye of the Devilsaur
Shoulder:
Shoulderguards of Intended Power
Cloak:
Fen-Yu, Fury of Xuen
Chest:
Tunic of the Unblinking Vigil
Bracer:
Dagryn's Fuselight Bracers /
Wristguards of Ruination
Gloves:
Gloves of the Unblinking Vigil
Belt:
Arrowflight Girdle
Pants:
Legguards of the Unblinking Vigil
Boots:
Puddle Punishers
Ring 1:
Kil'ruk's Band of Ascendancy
Ring 2:
Ring of Restless Energy
Weapon:
Hisek's Reserve Longbow
With this, you have 2 items that have hit or exp, bracers is a tough one, the choice depends on what our stat priority will be.
Trinket candidates:
Trinket 1:
Assurance of Consequence
Trinket 2:
Haromm's Talisman
Trinket 3:
Sigil of Rampage
Trinket 4:
Ticking Ebon Detonator
From what I can read, #4 is very hard to react to, it procs and if you have no focus = best moments gone. #3 seems like viable only on AoE fights.
So it looks like #1 and #2 are the choices, Both have a nice Agility proc and a niche to them, #2 doesn't seem to have a ICD for the proc, so this could be very overpowered for SV AoE? Unless they took care of that part too(Only procs against current target).