It depends on your comp, honestly - but generally I'd take skinning/herb for arenas for sure.
Arena is extremely comp dependent in terms of what gear is needed. Have several possible sets you can use for full damage, tanky burst, etc.
Not necessarily just what you're facing. Because, while important, it should theoretically be "impossible" to tell what you're going to queue against in an arena setting. With wargames, you have foreknowledge of what you're going to face so you could technically gear towards the enemy comp.
But let's take a few solid Ele 3v3 comps and look at the gear from Ele's PoV:
Hpally/Ele/Hunter - Maximizing your damage at the cost of stamina isn't going to be necessary here. Your CC is relatively high, your team's damage is high regardless of your gear choice. In this comp, your main presence in terms of damage is going to be from Fulmination Executes.
Conclusion: Stack some health. You don't need to be at 2k+ or anything, but being at 1800+ isn't going to be a bad idea here. You'll be sitting on your 7 stack for probably a while, so haste isn't going to be as big of a deal (especially with an early lifeblood to help rushing the 7 stack).
Disc/Ele/ArcMage - While it's possible that you might be the focus target in this comp, it's unlikely and would ultimately be beneficial for you to be the focus target. Your defensive play is going to be a lot stronger than the arcane mage or the disc priest. Your kills are going to be based around nova bursts, which are going to require frequent Fulms in coordination with your mage. Haste would probably be your best stat overall for this reason.
Conclusion: You shouldn't completely disregard stamina here, but substituting in a few DPS oriented items will ultimately help your team far more than stam stacking.
Hpally/Ele/Rogue: Your damage is crucial in terms of ranged pressure, you have a strong healer who can dispel you, you have a melee teammate who is a high priority swap target. Yeah, you guessed it - you're going to want to be in a high DPS set. I wouldn't recommend going below 1500~ health, as at that point a quick swap could actually global you. But certainly playing with high intellect/crit/haste gear is going to be extremely important for your team's success.
Conclusion: Go big or go home. Your rogue's damage may or may not be consistent due to kite potential. You're going to need to be keeping up constant burst on key targets and offhealing like there is no tomorrow. DPS set all the way.
The decision to swap Loom shield for Haste offhand is a very intense one, and should not be taken lightly. The shield provides a very much needed armor boost against Warriors, Rogues, and even Hunters. If you know the enemy comp is caster heavy and you don't need shield for hit cap, then go for it.
Using DPS trinkets instead of defensive trinkets (AGM, MoT, or even a pvp trinket) can be very risky, but if your damage is crucially important to the team it could provide a significant boost to your number of wins.