Probably M-Audio is probably best choice (beside Roland gear) for use with Sonar.

Fast Track C400 user here, no problems with it. Except that the latest versions of the driver won't let you set the buffer below 128 (apparently earlier versions allowed 64).

I just downloaded a new driver for my Fast Track Ultra and it looks like they have finally updated the GUI on the mixer. I am just reloading a new PC - so I haven't shaken it down yet - but this is a good sign! ( I think.)
Brian

I had great experience with delta 1010's from sonar 3 to X2.  The only issue I found was the control panel was a little finicky with Win8. There are no drivers for Win8 so that is probably the reason. But other than that, a fine interface.

A very important note about M-Audio is that now that they are no longer owned by Avid they are a great, responsive company with excellent support.  I've always loved their products but now I love the company again.

I seriously doubt there's anything left of M-Audio other than the brand - I mean, InMusic is a brand vulture, and it's loaded with gear companies that fell on hard times. Sure, some of it's brands still have some unique products, but with so much overlap, there's gonna be cost cutting and consolidation. Their first new products are re-badged Alesis interfaces. Nobody's fooled.

Separate subject, before I tout the M-Audio too much.  The Axiom will not work 'out of the box' as a controller.  It will not set up with ProTools and I've had so many headaches trying to tediously set it up with Sonar (8.5, X1, X2) that I eventually gave up and simply use it as a virtual piano with a pitch shift and mod wheel.  The interfaces have never given me an issue though :) 

I am a M-audio audiophile PCI 2496 soundcard user with Sonar X2 PE with windows 7. No problem here. Has been using that since Sonar 8.5. I have heard that M-audio has been very slow in updating their driver. So it is important that before you purchase any hardware you must make sure that the proper driver for your operating system is available for download from their website.
 
One minor annoyance was that the use of a particular software (I forget which one) tends to make the m-audio driver's control panel disappear. It was latter resolved by visiting M-audio's support website and they mention something about going through MSconfig setting. I had never experience that again when and updated driver was installed.
 
Other than that I am very have happy with my M-audio soundcard. It's advantage is that it is very stable, quiet, and fast. It's speed and low latency (128ms) allows me to enjoy playing softsynths with ease. That is my experience. My other interface is Cakewalk's UA25EX.

+1 on the slow to update drivers.  They still don't have a Win8 version of the FW-Solo.  It seems to take them the best part of a year to catch up with OS releases.
 
Although the Win7 driver worked pretty well, when I upgraded my interface, M-Audio was not even on the list.

I've been using the M-Audio Firewire 1814 since SONAR 5.  It's been rock solid for me although I have been using the ASIO drivers not WDM.  Anyway.....no complaints here!
 
Best to All!

Dave