I currrently only have the best spinner tool, and I use that in conjuction with article wizard to produce my content with. However, I have just been to a webinar with Amin Motin on the powers of the article builder and I must say I was immpressed.
If, your looking to create a lot of content for article marketing, and you already have PLR to use for this purpose, then using the best spinner can help with that task. You must still remember to take the time to proof read all the content before you publish it as no software is better than the human eye for editing
Once you can afford it, investing into the article builder can help you create content faster providing your niche is within their category topics. However, even if it is not you can always suggest topics to their team of writers which can then as updates take place get added in there.
Just remember, these tools are created to help save people time with their everyday writting tasks, however they will not do all the work for you on their own you still will have to master how they work and use them to their full potential.
I hope my answer helps you further with the choice decesion process on these 2 great software tools