Not really sure how to answer because what is easy to one, may not be easy to another. What and where you plan to grow are big factors also. For someone that doesn't want to build there own system the aero garden, or any other everything you need in a box kit is probably easiest. But for me I find it so simple to build my own systems that, that would be a waist of money for me. Here is a link that explains the different type of systems and how they work if it helps you:
Types of Hydroponic Systems
I also don't know what type of budget you will be working with. That would also be a big factor to consider. But any ready to go system will cost more than it would to build one like it. I built
this 4 plant system for about $80 including the
pump. Some ready to go systems may include some
nutrients and/or pH testing kit, and adjusters, but that's easy enough to get separate.