Hello,
I currently own Sonar X3 Studio and I am in the market for a new MIDI controller keyboard.  So far I have found two that are in my price range, the Roland A 800 Pro and the M-Audio Axiom Air 61 which are both available on Amazon ($292.49 for the Roland and $379.00 For the M-Audio).  Are there others that I should consider or would it be better to purchase the Roland as I understand that it was designed around Cakewalk software.  Are there others that are better than the Roland that would also work without too much difficulty with Sonar X3? 
Thanks for any advice you might be able to give,
Robert
PS I just found out about the Novation Impulse 61, does any one know anything about it and how well it would work with  sonar X3? Amazon is currently selling it for $308.95.

I think this one combines a lot of features at the price point and it's lower than the Roland A 800 Pro. If you can wait for some reviews later, do check this out :
 
http://www.soundonsound.com/news?NewsID=16948

After watching this.. I'm not sure what is the correct price..
 
http://www.sonicstate.com/news/2014/01/23/namm-2014-behringer-motor-61-moving-faders/
 
According to the SOS video, 49 keys : 249/=, 61 keys : 299/=
 
While the Sonic State video, 49 keys : 349/=, 61 keys : 449/= 
 
Edit :
http://www.sweetwater.com/insync/behringer-motor-series/
Sweetwater price must be correct ? :)

Either of those choices should serve you well. I have a slight preference for the feel of Roland keyboards over Axiom. The Axiom's touchpads are a little nicer, though, if you plan on using them for playing drum parts. Both have one essential feature for smaller keyboards that you might not think about: nice big octave-shift buttons.

I just replaced my 25 year old Roland 49 key controller ( PC100?) with what appears to be the same thing the A49. I too like the feel over most others, How can plastic have a feel?? 
Anyhow for me it is perfect in size. I see no use for more keys because the octave shift is right there. I like it's compact size. It was only $130 from Tom Lee Music. 
 
Only disappointing feature is they chose USB power, I would have preferred a proper power supply with standard "boss type" connection. So if you use the standard MIDI connections, you'll need to use a USB type ( 5V) power supply but with a very uncommon type B connector. So this makes it hard to use this keyboard in a non computer based set up.  
But for computer set up USB is now the standard.
 
The other disappointing missing feature is you would figure a keyboard branded "Cakewalk" would come with some ready to go Sonar friendly transport buttons. 
 
Best feature is the very solid feeling Mod/joystick lever which I use a lot with Organ patches. 
There's a cool little proximity sensitive Theremin device that make most synths go weird as you move your hand up and down over it.  You can patch it to any controller like Volume. 
The octave and transpose is super user friendly on this, unlike my old model. 

The new Behringer units look nice, especially for $299, which I confirmed with my guy at Sweetwater...  I too will be upgrading my old Maudio pro88 which I love but seems determined to loose connectivity every five minutes for no discernible reason at all and it's getting real tiresome to turn it off and on again a dozen times an hour.

i just got the m-audio keystation 49es. it's bare bones and does exactly what i want which is make noise when i hit the keys. if you are a keyboard pro then you'd probably want something bigger/better. just thought i'd throw in for people who are going entry-level but would like something that isn't "casio."
 
http://www.m-audio.com/products/en_us/Keystation49es.html
 
i got it for half-price (or less? can't remember) though so it was a no-brainer. works as advertised. keys are non-weighted, a bit "spongy" going down and "springy" coming up but very usable.

It's worth taking a look at older used controllers. The hardware is usually more robust. It depends  if the main function is use as a higher quality key bed or if lots of controllers are needed. I still use a very trusty Kurzweil Midi Board. Only a couple of CC controllers but the real time velocity offset on a slider is something I wouldn't want to be without. Plus it has poly aftertouch and full wooden keys.

Lots out there.

I use the Line 6 KB37 for many reasons. I have a laptop. It's with me whenever I need it, wherever I am.

Here are two good views why it's worthy of your consideration:
http://www.youtube.com/watch?v=cRpCXWSC8TE

http://www.youtube.com/watch?v=zwBR1OfHRtM

I just got the novation impulse 25.  Works fine.  I'm not using automap - well, automap but for some reason it hooked up to SONAR X1.  Which is fine, ACT seems to be working well on X3.
 
@