The manual with EQ6 is very user friendly, however you are limited on how many times you can install it.
EQ7 has more bells and whistles, and unlimited installations.
EQ5 has less options, unlimited installations, I haven't seen the manual so cannot comment on that.
From what I have seen, the upgrades are fairly spendy, I don't know if it is cost efficient to buy a version and then plan on upgrading....
If you go to the EQ website, there is a pretty good explanation of all of the versions. Feel free to call their customer service too. You can tell them what it is you want to use the program for, and they can help you with deciding on which version will meet your needs :D They are very kind, patient, and helpful :D:D:D
For me, EQ6 does all that I want. I did purchase EQ7 and maybe after playing with it some more, I may change my mind LOL