HP2 is right on with the offset bushings, probably the easiest way to improve your handling and deal with the limitations of the stock UCA's. And unless you really start to push the car handling wise, you'll probably never notice any flex or bump steer.
Tubular UCA's are nice, they do offer some advantages that the stock arms don't as far as adjustability, strength, and improved alignment numbers, but they're pretty expensive. I think the Hotchkis uppers are by far the best as far as design, they relocate the front frame attachment point to reduce the anti-dive that the factory put in for the station wagons and reduce bump steer etc. But they're also the most expensive, and they can be more difficult to set up because they replace the front camber bolt with a non-adjustable mount, so all the adjustment has to be done with the heim. Magnumforce makes a "double adjustable" UCA that gets around the problem of setting up the heims, allowing you to make adjustments with the arms still on the car. It's a way nice feature, but if you're only going to set the car up once or twice its probably not worth it.
There's quite a few other makers out there, FFI, Just Suspension, RMS etc. As long as you stick with a well known source, all of the arms are pretty high quality. I would say to pay attention to the shape of the arm though. Some of the UCA's out there are shaped more like a "U" than an "A", and that reduces the amount of clearance you have for rims and tires. For stock sizes its not an issue, but if you want to clear larger rims with more backspace the "U" shaped UCA's can be a limitation. I had a set that I had to remove just for that reason, they interfered with my 17x9" rim with 5" backspace. But, that's a pretty big rim.
