As mentioned here many times, definitely use ASIO. 

WDM used to be better for me back in the day with earlier SONAR and Echo interfaces, but ASIO now is the best for me as well.
 
 
Lance

Andrew Rossa [Cakewalk]
As mentioned here many times, definitely use ASIO. 

Well, the Cakewalk support site for Hardware setup mentions WDM for Edirol (by Roland), as well as Tascam that I have.  Here are two such examples.  Perhaps this site is outdated?
 
http://www.cakewalk.com/Support/hwsetup.aspx

Edirol also provides WDM/KS drivers. If you experience problems in the ASIO Driver Mode, you may want to consider using WDM as an alternative.

Tascam Audio Interface setup for SONAR X1
Click Edit > Preferences
Under the Audio section on the left, click on Playback and Recording
From the 'Driver Mode' dropdown select WDM/KS and then click Apply
 
 

Reed,
 
   Just in case you are unfamiliar, you can search on WDM vs ASIO (these both have the best latency for recording). Big picture, ASIO dedicates itself to whatever grabs it first, and WDM will allow them to be shared. Depending on your application, this difference may drive you down the WDM path. Also, ensure you have the most current drivers for your hardware/operating system combo. ASIO is typically preferred, and be sure to use drivers specifically for your hardware. I would recommend staying away from "ASIO4ALL" in case you happen to run across this some place.
 
Michael

Some sound card drivers will preform in a better in a DAW with WDM drivers and some with ASIO drivers.
You need to try both to determine what's better for you. do not take the word of some guy saying "ASIO always works better for me", as each situation is different!
 
CJ
 

+1 on CJ
 
I missed the "operational test" part :(