I would support Paul Morrison's recommendation of Sequencher. I have
been using this software for four years. It is so intuitive that within
ten minutes of opening the software I was able to start editing
sequence, yet I am still discovering new useful features.
Other than its ease of use, the best Sequencher feature is the support
that one gets from GeneCodes. They are responsive to customer feedback
and always willing to consider new applications for the software.
Good luck with your decision.