Nifft said:
Greatsword! Especially if it's a Thundering Greatsword. Good base damage, good bonus damage type.
If you have a high Strength (14 or higher) you'll do a lot more damage with a greatsword.
-- Nifft
Ugh. Thundering. You need IC: Greatsword to make it even vaguely useful; sure, it's an extra d8 and a Fort save to avoid being deafened, but it's a piddly DC and Deafness isn't that penalizing except to spellcasters (with the 20% spell failure for verbal component-using spells). I don't really see how that's worth a +2 enhancement. I'd take Screaming any day.
Hrm. Both will have their uses. However, doing it two-weapon style (including going down the extra attacks hierarchy), you get twice the attacks, at a 10% penalty (-2, remember, unless you're a high-level Tempest), with about the same damage if all your attacks hit.
Adding in sneak attack would tip the balance, but sometimes you NEED that extra +2 to hit, because, well, that big nasty monster you're flanking has so little Dex that it doesn't matter that you're flanking it.
I'd be prepared to do both. In fact, that's what my character does; he switches between a two-hand weapon and a pair of shortswords as need be, or when he feels like it. I almost wish I had EWP: Kukri, as we just saw a NICE pair of +5 Vorpal Kukri (with matching set of Scabbards of Keen Edge). We don't *have* them, but they're quite nice.
Brad