Of the list of devices I've seen so far, the only one I can recommend is the 8Pre.
The Presonus FIREPOD tends to have lots of hardware failures. The FireStudio reportedly has lots of compatibility problems.
The M-Audio FW1814 has some quirkiness. It isn't the most horrible thing I've dealt with, but its drivers are quirky enough that I probably wouldn't recommend it. It's BeBoB, with all the quirks that the BeBoB chipset brings with it.
The Onyx 1200f uses the TI chipset, so it should be pretty solid, AFAIK, but don't buy one if you're using Mac OS X 10.4.10. Apparently, support for the TI chipset broke pretty hard in 10.4.10. No idea if the next update will fix that or not; the rumor sites suggest that it probably will, but that's all I have to go on in this matter.
I have no opinion on the Focusrite stuff. It's BeBoB, which is good and bad---good in that it is a very popular chipset, so support is fairly solid---bad in that IIRC it is pretty funky as chipsets go.

It's probably reasonable hardware, though; I have no firsthand experience either way.
If I were choosing, I'd go with either the 8Pre (Phillips chipset) or something based on the TI chipset... maybe the Oxford chipset as long as it doesn't say Behringer on the front.
