There are many personal income tax software packages available in the Canadian market. In my opinion the best overall software is Studio Tax. I have tested it for the last two years. It worked very well and it is free. The link is given below.
This year, they are also providing a trial version for professionals. You can prepare first 20 returns free and use e-file facility as well. Since I am starting a part-time tax practice 2011, it will be an opportunity for me to test the software and try e-filing. I will post my review comments once I have used the professional version of the software. Here is the link for the professional version.