You can use Maxwell latest version or Jmag. Both are good however Maxwell is preferred usually. If you want to do 3-D simulation then JMAG is preferred. However for doing simulations you have to buy license of these softwares. There is another software which is free, it is called FEMM. The design process will be a little difficult i suppose but you can get your results in FEMM too. 

Dear Siva Subramaniyam,

This is a tricky questions as many software have been developed in that field. No software can be marked as best, since it depends on what you are willing to do and how experienced you are (in computer simulations and in electrical machines).

To design a PMDC or BLDC motor, you could need to:

Do not hesitate to contact me for more informations. I do not work for these software companies, I am an end-user, developing my own routines based on what they propose.

maxwell is the best. like Linux over windows