I would have to say that Magenta is my favorite and most accessible company and there are a couple of others that I am finding more and more that I like, ones that lean towards the old Shakespearean themes and such.  I also have  become addicted to the wonderful home demo company of Stampin Up.  Great stamps, great rep I have to order from and so many ideas!! Stamping is kind of an obsession for me, so is collecting all the awesome and different kinds of paper for layering, be it healthy or not and I really enjoy most of my end results. Since early spring of 1999 I have been part of a wonderful e-mail list(with a small break for a bit) with wonderful stampers that are full of ideas and always willing to share their knowledge.  And so much talent on the list of people that have been published in numerous stamping magazines.