I like the Potenzas fine, and I've had them almost a year. They have okay traction, but I get them loose a lot when applying gas in turns (no more than any other tire I guess). They are pretty soft rubber, so as long as you maintain speed in a turn, you'll have good traction (there are exceptions). I like that people recongnize the name. Sometimes it's like I'm driving around with the Rolex of tires the way older people react to them.
If you keep them clean, they hold tire oil really well and can look DARK black.
Falken's are good especially if you auto-x alot. SCC magazine always gives them good reviews. They have alot of grip and are fairly cheap compared to other brands. I've heard people say that the sidewall's are very stiff and it is hard to get them mounted because of that. But I have had no problems and the ride wasn't really harsh when I had the 205-40's.