What's your budget? It really depends on what you're willing to spend for the gradually diminishing returns of the top drives.
If you can afford the vertex comfortably, I would take that one for the synchronous NAND based peace of mind. It's not just that asynchronous suffers from reduced incompressible data rates (that's not a huge deal really, unless you were intending on copying a lot of mp3s etc back and forth) but there are suggestions that they suffer more performance degradation when they get filled up than synchronous [search synchronous vs asynchronous on these forums for more info].
If money is no object, then look at the vertex 3 max iops, patriot wildfire and mushkin chronos deluxe. They are the fastest around, and use toggle NAND which also reduces these problems. The first two do sell at a bit of a premium though.
All of that said, you'll get a great experience from the agility 3 anyway and if you're coming up from an hdd it will be a huge difference. Even professional reviewers can't really tell any of the new drives apart in actual use.