Chessmaster hasn't been available in the retail channels for years and is no longer supported. Nice tutorials, lousy engine; not worth the crazy prices people are asking for it (and no guarantee if you buy used that it will run).
Fritz is the new standard. Versatile, powerful, upgradeable engines and like all ChessBase products, totally nonintuitive to learn. Good thing there are tutorials available. If money's tight, buy an older version and save a bundle.
ChessKing. Delightfully eccentric and really easy to use. Lots of practice exercises set up to appeal to the kid in all of us. Stuck with whatever engine comes with it; luckily Houdini is more than good enough in whatever version you buy. It is Russian type software though so it's a little quirky.
HIARCS. This was originally developed for the Mac, I believe, and retains the ease of use that some Apple products are famous for. Nice clean interface. You can play the computer in either full or dumbed down to your level and start from any of 200 common openings. Search the database by clicking in a position and voila, there are all the games. Only handles PGN files though so you'll be switching databases in and out which is luckily easy to do. Small ones load quick but my 2million games "base takes a few minutes.
Too bad you can't come over to the house and try them out. Good luck making up your mind. I obviously couldn't. 
Hello there,
it is confusing for most of us to take the best SW from the market. Which is the best according your experience - Chessmaster 9000, or 10th edition; Fritz Chess 13..., etc.
Which of these products can be installed to Win 7/8?
There are enough powerfull sw products for learning and practising and of course improving our skills, the question is 'which one'?
Thanks a lot for your opinions!
happy New Year