Asus Xonar D2X
Asus Xonar STX
I was just doing research on sound cards yesterday (true story) and I like the Asus Xonar lineup more than the Creative X-Fi. X-Fi has a limited sample rating of 24bit 96Khz on all except the Titanium Fatal1ty Champion card. Most, if not, all Asus Xonars support 24bit 192Khz.
The D2X and STX has a sound to noise ratio of 118dB, while the Titanium Fatal1ty Champion has a SNR of 109dB.
The downside for Asus Xonars is that it doesn't "natively" support EAX 5.0. EAX 5.0 is supported through a hack, so it's not a true 1:1 replica of EAX 5.0. X-Fi on the other hand support EAX 5.0 natively.
Now, I have no idea what EAX, SNR and sample ratings are. But I know that the higher either are, the better.
I recommend the D2X over the STX (over any X-Fi) because the STX is more towards studio rather than home theater and gaming (from what I understand and see).
PS. Creative PCI Express Sound Blaster X-Fi Titanium Fatal1ty Champion Series is the longest and ugliest name EVER.
EDIT: Just read up some reviews on the D2X and it says that EAX 3.0 and up are proprietary to X-Fi. So only X-Fi cards will carry any EAX 3.0 or higher. I also read that EAX is a MUST for hardcore gamers that want to hear an enemy breath from a mile away. But Asus uses a hack that tells a game that it supports EAX 5.0 and is able to get those additional streams.
I still recommend the D2X.