Landslide, mainhand. Hurricane, offhand.
Doubtful unless they're unable to stack. Assuming similar proc mechanics, one will be ahead of the other and likely be so for both weapons, the question really comes down to which it will be. And thats a pretty open question since we don't know relative stat values fully for Cata yet, much less mechanics of the weapon enchants
The one situation in which a mixed enchant setup may be optimal is if Hurricane can proc off of poison procs and Landslide can't, but has higher uptime on a weapon hitting with Instants.
That said, it's unlikely, and while the budgeting appears
similar, it should be noted that Landslide is a substantially higher (profession) level enchant, requiring much more expensive mats, and a recipe only available from a shard trade in. By contrast, Hurricane is a leveling pattern. They've also both demonstrated some weird
stacking behavior on Beta - i.e. Landslide is honest to god stacking
. Like, 1 buff icon with a little number, and I've seen it stack to 3. Hurricane meanwhile, appears to be able to generate 3 independent buffs from MH swing, OH swing, and Spell hit procs... Something funny is going on with both and it's going to make the enchant choice interesting for a while...