Firstly- there are better tires out there than the Goodyear LS2's that come stock. When you say traction- if you are looking for snow and or off road capable tires- that narrows it down, as there aren't too many in our size. If you're looking for road performance tires- there are too many to list.
Best thing to do is go to TireRack.com and put in the Beca, then read the reviews. Paying close attention to the kind of vehicle the driver is putting them on.
I consider myself a "tire slut". If they build them, I want to ride them!!! I found found some awesome tires over the last 10 years, but you need to understand what you want out of them. Many years ago I ran Michelin XWX tires on my Porsche's - Formula 1 Compound C and most rigid sidewall ever built. These tires were marvels on hot sunny days, and might as well have been ice skates in the rain. Oh yeah, I got 5K miles out of them.
One thing I will conjecture about the B9 is that the suspension is pretty tight and there is minimal body roll. This coupled with the larger than average tire width would suggest the car will perform better with harder compound and a slightly softer sidewall. But for bad weather driving this is a bad combination.
I have to go back to saying I think the LS2's are a very reasonable all-season compromise for this car. We had a set before on a Nissan I hated. I took them off early and tossed them. But these are redesigned and so far no problems (6K miles). And for us they have worked great in EXTREMELY bad storms in Sierra.
The only other tire I have heard that handles all conditions well and still offers a bit of sportiness is the Yoko Geolander, but have not driven it.
I ordered 20" OZ Canyons today with 255/45/20 Yokohama Spec-X's. They should be on Saturday (when I take delivery of my new '07). I'll post reviews. I'll be coming from an '06 Outback XT with BBS RK's and 225/55/17 Nokian WR's (for whatever that is worth). I too put a lot of weight in tire choice....before than I had an '05 STI with Michelin Pilot Sports on Stock BBS's......loved that set-up.