these are all very good brands that make low end, moderate end, and high end machines.
i've always found it easier to decide by first figuring out what i want to use the machine for and what features do i need the machine to have in order to maximize said use.
then using the brands you've listed find the models that have those features and compare number of features to price and test drive the models i'm interested in.
finally i'd settle on 2 machines and i'd start a price war between the stores to get the best deal and service contract.