I've been very satisfied with RME PCMCIA + Multiface (yes, a dinosaur, I actually don't use it so much since I got a newer laptop that does not have a PCMCIA slot). Also, the PCI version of RME (HDSP) with Multiface II has been very good to me. In the past, I used M-Audio Delta 44 (PCI) and now also own PreSonus AudioBox USB that I am somewhat satisfied with. The latter two are not really pro... The PreSonus generates some faint glitches, I presume influences by the GPU (it mostly happens when I move windows around or other things that cause screen redraws. Probably some IRQ issue or MoBo or something (it's a laptop...). Moreover, the PreSonus AudioBox USB is a stereo card. I recently purchased PreSonus AudioBox VSL 44 (USB 4 I/O) but they don't work with Linux out of the box and I did not make it to work so returned it. I've had luch with Edirol and PreSonus firewire devices but it seems to be a moving target because in some situation it was a pain to make FW interfaces work. Also, they did not behave very well with Jack.
The company I work at has purchased recently RME MADI but we also got a Mac so I am not sure if I will be able to test those on Linux, although I am very inclined to do so.
./MiS