I'm not sure that you can have both - so pick either the best or the most economical.
Auto Enginuity is what I have. It's not cheap - but it is amongst the best out there - if not the best. Very easy to use and will supply way more information than you could ever want. I have the laptop version, full Ford module.
I first got the program after being involved in the Diesel forum communities. Not only will it tell me every thing about my truck down to exactly how much fuel is in my tank - but will run tests on my glow plugs, injectors, etc etc. Has a whole set of key on/key off tests.
As far as I am concerned it's been worth every penny. And oh yeah - since my whole family drives Fords - I'm pretty well set.
Ron