Impossible. There is no "best" sound card, but there are good ones. Sign up on the Samplitude Pro Forum and do a search to see what the pro's use. Or ask the question there, but I would word is as what is a good sound card and indicate how you intend to use it - single/double input, multi-input, etc. Do some research on the web for different sound cards.
They will likely tell you that it is not just the sound card, but also the Asio driver and the other equipment, so you need to look at the entire chain.
It depends on what you mean by "sound card". If you mean an actual sound card, like the one that you install in your PC tower, then I would not recommend using that at all. Use an external USB audio interface like a Focusrite Scarlett Solo or a Native Instruments Audio Kontrol (both of which I own and are excellent).