I still own a 0404 USB (for antequarious reasons heh)....it served me well.In it's priceclass it was for a certain time a very good ADC.The old beta drivers still work...sadly these PC drivers are actually total crap and outdated as well ...However, i could run it on Win 7 pretty well at 9-10 ms latency.
But according to the topic title i'd never call this device "really the best" or shift it into proximity of ADC's like the Benchmark DAC1,the RME Fireface UC ,or the the Lavry AD11 or even the smallest Weiss DAC for example.Even the older RME Babyface blasts the emu0404 usb out of it's socks.I switched a moon ago to the RME Fireface UC and in terms of sonic fidelity and neutrality , drivers, latency, mixer software,usability, support etc ...the emu doesn't even play in 2.league while the Fireface UC plays already champions league .If anyone is still on the opinion the 0404 is "The Best " ...well, put your helmet on and take your proteine pills .
However if you're on a tight budget and you can get a used emu 0404 for say 50 bucks ...i''d say it's worth it