Hi Babahi,
here's a good review that compare the 3 main DAW program:
http://www.tweakheadz.com/comparing_...logic_vst.html
The comparison is fair. There's annotation for Sonar as well.
I used to work with Cakewalk Pro Audio 9.0 and convert to Logic Platinum about 6 months ago. Dave's comment about Cakewalk/Sonar interface is funny since I felt exactly the opposite! Cakewalk and to a lesser (much lesser) extent Sonar was always "crippled" by an overly simplistic arrange window (you can almost recognize old win3.1 in the layout!). Given a screen resolution Logic provides me with WAY more "real estate". Now Sonar is very improved but I still feel it wastes a lot of space and the *information is "packed" in the arrange window which is the most important.
Of course it is all a mater of taste and of workflow. For me Cakewalk/Sonar always appears to me like a program not a musical instrument or tool. On the other hand Logic I see as a musical instrument. Cubase interface simply didn't click for me.
The software plugins "effects" in Logic shamed the Sonar equivalent the Platinum-Reverb in particular.
Dave's comment about complexity is partially true. On the midi side things CAN get complicated if you choose to do so but you don't have! Since my midi "environment" is setup I hardly touch it. The audio side is simpler to use and more intuitive than Sonar/Cakewalk.
Don't get me wrong the 3 programs are outstanding but each have their own strength. The channel editor in Sonar is very flexible and integrated with the arrange track. In Logic it is also integrated with the arrange but the curve are simpler.
Latency-wise I a much better performance with Logic than I got with Cakewalk. I can also play slightly more audio track.
The audio card you use should also be a factor in your decision some work better with some program than other. I'm using a Delta 44 and it worked fine with both.
If you can try them the best way is to chose the one you feel most at home with. Cakewalk always had the stigmata of being "less professional" than Cubase and Logic. I don't think, functionality-wise it is still true, except for the effects which are not yet up to par.
Good Luck
JFT