And sometimes there are software you find irksome and think things could have been better. In any case, I always like to try out a few alternative software choices before I settle with any particular application mainly for two reasons: One, you would never know how good or bad the one you are using is until you try some alternatives and two: a bit of choice and competition can only be for the good of us users! Your motivation might be different: perhaps you want to find a free software that does the same task as the paid software you are using or maybe your favorite Windows application is not available on Mac or Linux.
Whatever maybe the reason, here are some sites that you can use to find alternative software and suggested applications.
My personal favourite is osalt.